Author name code: fossat ADS astronomy entries on 2022-09-14 author:"Fossat, Eric" ------------------------------------------------------------------------ Title: Dome C coherence time statistics from DIMM data Authors: Aristidi, E.; Agabi, A.; Abe, L.; Fossat, E.; Ziad, A.; Mékarnia, D. Bibcode: 2020MNRAS.496.4822A Altcode: 2020MNRAS.tmp.1986A; 2020arXiv200613778A We present a reanalysis of several years of DIMM data at the site of Dome C, Antarctica, to provide measurements of the coherence time τ0. Statistics and seasonal behaviour of τ0 are given at two heights above the ground, 3 and 8 m, for the wavelength λ = 500 nm. We found an annual median value of 2.9 ms at the height of 8 m. A few measurements could also be obtained at the height of 20 m and give a median value of 6 ms during the period June-September. For the first time, we provide measurements of τ0 in daytime during the summer, which appears to show the same time dependence as the seeing with a sharp maximum at 5 PM local time. Exceptional values of τ0 above 10 ms are met at this particular moment. The continuous slow variations of turbulence conditions during the day offers a natural test bed for a solar adaptive optics system. Title: More about solar g modes Authors: Fossat, E.; Schmider, F. X. Bibcode: 2018A&A...612L...1F Altcode: Context. The detection of asymptotic solar g-mode parameters was the main goal of the GOLF instrument onboard the SOHO space observatory. This detection has recently been reported and has identified a rapid mean rotation of the solar core, with a one-week period, nearly four times faster than all the rest of the solar body, from the surface to the bottom of the radiative zone. Aim. We present here the detection of more g modes of higher degree, and a more precise estimation of all their parameters, which will have to be exploited as additional constraints in modeling the solar core.
Methods: Having identified the period equidistance and the splitting of a large number of asymptotic g modes of degrees 1 and 2, we test a model of frequencies of these modes by a cross-correlation with the power spectrum from which they have been detected. It shows a high correlation peak at lag zero, showing that the model is hidden but present in the real spectrum. The model parameters can then be adjusted to optimize the position (at exactly zero lag) and the height of this correlation peak. The same method is then extended to the search for modes of degrees 3 and 4, which were not detected in the previous analysis.
Results: g-mode parameters are optimally measured in similar-frequency bandwidths, ranging from 7 to 8 μHz at one end and all close to 30 μHz at the other end, for the degrees 1 to 4. They include the four asymptotic period equidistances, the slight departure from equidistance of the detected periods for l = 1 and l = 2, the measured amplitudes, functions of the degree and the tesseral order, and the splittings that will possibly constrain the estimated sharpness of the transition between the one-week mean rotation of the core and the almost four-week rotation of the radiative envelope. The g-mode periods themselves are crucial inputs in the solar core structure helioseismic investigation. Title: Detection of g modes in the asymptotic frequency range: evidence for a rapidly rotating core Authors: Ulrich, Roger K.; Fossat, Eric; Boumier, Patrick; Corbard, Thierry; Provost, Janine; Salabert, David; Schmider, François-Xavier; Gabriel, Alan; Grec, Gerard; Renaud, Catherine; Robillot, Jean-Maurice; Roca Cortés, Teodoro; Turck-Chièze, Sylvaine Bibcode: 2017SPD....4810906U Altcode: We present the identification of very low frequency g modes, in the asymptotic regime, and two important parameters: the core rotation rate and the asymptotic equidistant period spacing of these g modes. The GOLF instrument on the SOHO space observatory has provided two decades of full disk helioseismic data. The search for g modes in GOLF measurements has been extremely difficult, due to solar and instrumental noise. In the present study, the p modes of the GOLF signal are analyzed differently, searching for possible collective frequency modulations produced by periodic changes in the deep solar structure. Such modulations provide access to only very low frequency g modes, thus allowing statistical methods to take advantage of their asymptotic properties. For oscillatory periods in the range between 9 and nearly 48 hours, almost 100 g modes of spherical harmonic degree 1 and more than 100 g modes of degree 2 are predicted. They are not observed individually, but when combined, they unambiguously provide their asymptotic period equidistance and rotational splittings, in excellent agreement with the requirements of the asymptotic approximations. P0, the g-mode period equidistance parameter, is measured to be 34 min 01 s, with a 1 s uncertainty. The previously unknown g-mode splittings have now been measured from a non synodic reference with a very high accuracy, and they imply a mean weighted rotation of 1277 ± 10 nHz (9-day period) of their kernels, resulting in a rapid rotation frequency of 1644 ± 23 nHz (period of one week) of the solar core itself, which is a factor 3:8 ± 0:1 faster than the rotation of the radiative envelope.Acknowledgements. Ulrich is first author on this abstract due to AAS rules, Fossat is the actual first author. SOHO is a project of international collaboration between ESA and NASA. We would like to acknowledge the support received continuously during more than 3 decades from CNES. DS acknowledges the financial support from the CNES GOLF grant and the Observatoire de la Côte d’Azur for support during his stays. RKU acknowledges support from NASA for his participation in this project and thanks John Bahcall for enthusiastic encouragement for the g-mode search. Title: Asymptotic g modes: Evidence for a rapid rotation of the solar core Authors: Fossat, E.; Boumier, P.; Corbard, T.; Provost, J.; Salabert, D.; Schmider, F. X.; Gabriel, A. H.; Grec, G.; Renaud, C.; Robillot, J. M.; Roca-Cortés, T.; Turck-Chièze, S.; Ulrich, R. K.; Lazrek, M. Bibcode: 2017A&A...604A..40F Altcode: 2017arXiv170800259F Context. Over the past 40 years, helioseismology has been enormously successful in the study of the solar interior. A shortcoming has been the lack of a convincing detection of the solar g modes, which are oscillations driven by gravity and are hidden in the deepest part of the solar body - its hydrogen-burning core. The detection of g modes is expected to dramatically improve our ability to model this core, the rotational characteristics of which have, until now, remained unknown.
Aims: We present the identification of very low frequency g modes in the asymptotic regime and two important parameters that have long been waited for: the core rotation rate, and the asymptotic equidistant period spacing of these g modes.
Methods: The GOLF instrument on board the SOHO space observatory has provided two decades of full-disk helioseismic data. The search for g modes in GOLF measurements has been extremely difficult because of solar and instrumental noise. In the present study, the p modes of the GOLF signal are analyzed differently: we search for possible collective frequency modulations that are produced by periodic changes in the deep solar structure. Such modulations provide access to only very low frequency g modes, thus allowing statistical methods to take advantage of their asymptotic properties.
Results: For oscillatory periods in the range between 9 and nearly 48 h, almost 100 g modes of spherical harmonic degree 1 and more than 100 g modes of degree 2 are predicted. They are not observed individually, but when combined, they unambiguously provide their asymptotic period equidistance and rotational splittings, in excellent agreement with the requirements of the asymptotic approximations. When the period equidistance has been measured, all of the individual frequencies of each mode can be determined. Previously, p-mode helioseismology allowed the g-mode period equidistance parameter P0 to be bracketed inside a narrow range, between approximately 34 and 35 min. Here, P0 is measured to be 34 min 01 s, with a 1 s uncertainty. The previously unknown g-mode splittings have now been measured from a non-synodic reference with very high accuracy, and they imply a mean weighted rotation of 1277 ± 10 nHz (9-day period) of their kernels, resulting in a rapid rotation frequency of 1644 ± 23 nHz (period of one week) of the solar core itself, which is a factor 3.8 ± 0.1 faster than the rotation of the radiative envelope.
Conclusions: The g modes are known to be the keys to a better understanding of the structure and dynamics of the solar core. Their detection with these precise parameters will certainly stimulate a new era of research in this field. Title: Monitoring the optical turbulence in the surface layer at Dome C, Antarctica, with sonic anemometers Authors: Aristidi, E.; Vernin, J.; Fossat, E.; Schmider, F. -X.; Travouillon, T.; Pouzenc, C.; Traullé, O.; Genthon, C.; Agabi, A.; Bondoux, E.; Challita, Z.; Mékarnia, D.; Jeanneaux, F.; Bouchez, G. Bibcode: 2015MNRAS.454.4304A Altcode: 2018arXiv181107585A The optical turbulence above Dome C in winter is mainly concentrated in the first tens of metres above the ground. Properties of this so-called surface layer (SL) were investigated during the period 2007-2012 by a set of sonic anemometers placed on a 45 m high tower. We present the results of this long-term monitoring of the refractive index structure constant C_n^2 within the SL, and confirm its thickness of 35 m. We give statistics of the contribution of the SL to the seeing and coherence time. We also investigate properties of large-scale structure functions of the temperature and show evidence of a second inertial zone at kilometric spatial scales. Title: Study of the sub-AU disk of the Herbig B[e] star HD 85567 with near-infrared interferometry Authors: Vural, J.; Kraus, S.; Kreplin, A.; Weigelt, G.; Fossat, E.; Massi, F.; Perraut, K.; Vakili, F. Bibcode: 2014A&A...569A..25V Altcode: 2014arXiv1407.8190V Context. The structure of the inner disk of Herbig Be stars is not well understood. The continuum disks of several Herbig Be stars have inner radii that are smaller than predicted by models of irradiated disks with optically thin holes.
Aims: We study the size of the inner disk of the Herbig B[e] star HD 85567 and compare the model radii with the radius suggested by the size-luminosity relation.
Methods: The object was observed with the AMBER instrument of the Very Large Telescope Interferometer. We obtained K-band visibilities and closure phases. These measurements are interpreted with geometric models and temperature-gradient models.
Results: Using several types of geometric star-disk and star-disk-halo models, we derived inner ring-fit radii in the K band that are in the range of 0.8-1.6 AU. Additional temperature-gradient modeling resulted in an extended disk with an inner radius of 0.67+0.51-0.21 AU, a high inner temperature of 2200+750-350 K, and a disk inclination of 53+15-11 °.
Conclusions: The derived geometric ring-fit radii are approximately 3-5 times smaller than that predicted by the size-luminosity relation. The small geometric and temperature-gradient radii suggest optically thick gaseous material that absorbs stellar radiation inside the dust disk.

Based on observations made with ESO telescopes at the La Silla Paranal Observatory under program IDs 080.C-0541(C), 082.C-0893(A), 084.C-0848(B).Appendix A is available in electronic form at http://www.aanda.org Title: Twenty-five years of helioseismology research in Uzbekistan Authors: Ehgamberdiev, Sh. A.; Fossat, E.; Serebryanskiy, A. V. Bibcode: 2014JAHH...17...45E Altcode: The Ulugh Beg Astronomical Institute was involved in the IRIS helioseismology project from the mid-1980s through to the end of the project in 2001. This project aimed to study the deep interior of the Sun using Doppler spectral line shift measurements integrated over the whole solar disk. In order to obtain long, continuous observational data showing periodicity a network of six stations more or less regularly distributed around the globe and equipped with identical spectrophotometers was deployed. One of these instruments was installed on Mt Kumbel in Uzbekistan in 1988. In addition, from 1996 to 2002 the Ulugh Beg Astronomical Institute was involved in observations for the TON project, which was aimed at carrying out helioseismic studies of the subsurface structure of the Sun and its dynamics.

The participation of the Ulugh Beg Astronomical Institute in both projects was crucial not only for obtaining long-term observational data, but also for the scientific analyses of the observational data and the preparation of the resulting research papers. Many scientific results came out of these two projects, but more importantly, many graduate students used these projects to obtain their Ph.D.s. Title: Early South Pole Observations and the IRIS Network: The Quarter Century History of a Small Sodium Cell Authors: Fossat, E. Bibcode: 2013ASPC..478...73F Altcode: This is a brief list of snapshots along my personal scientific trajectory, which has interestingly met 30 years of the initial development of helioseismology. Title: New insights into the dust formation of oxygen-rich AGB stars Authors: Karovicova, I.; Wittkowski, M.; Ohnaka, K.; Boboltz, D. A.; Fossat, E.; Scholz, M. Bibcode: 2013A&A...560A..75K Altcode: 2013arXiv1310.1924K Context. Asymptotic giant branch (AGB) stars are one of the major sources of dust in the universe. The formation of molecules and dust grains and their subsequent expulsion into the interstellar medium via strong stellar winds is under intense investigation. This is in particular true for oxygen-rich stars, for which the path of dust formation has remained unclear.
Aims: We conducted spatially and spectrally resolved mid-infrared multi-epoch interferometric observations to investigate the dust formation process in the extended atmospheres of oxygen-rich AGB stars.
Methods: We observed the Mira variable AGB stars S Ori, GX Mon, and R Cnc between February 2006 and March 2009 with the MIDI instrument at the VLT interferometer. We compared the data to radiative transfer models of the dust shells, where the central stellar intensity profiles were described by dust-free dynamic model atmospheres. We used Al2O3 and warm silicate grains, following earlier studies in the literature.
Results: Our S Ori and R Cnc data could be well described by an Al2O3 dust shell alone, and our GX Mon data by a mix of an Al2O3 and a silicate shell. The best-fit parameters for S Ori and R Cnc included photospheric angular diameters ΘPhot of 9.7 ± 1.0 mas and 12.3 ± 1.0 mas, optical depths τV(Al2O3) of 1.5 ± 0.5 and 1.35 ± 0.2, and inner radii Rin of 1.9 ± 0.3 RPhot and 2.2 ± 0.3 RPhot, respectively. Best-fit parameters for GX Mon were ΘPhot = 8.7 ± 1.3 mas, τV(Al2O3) = 1.9 ± 0.6, Rin(Al2O3) = 2.1 ± 0.3 RPhot, τV(silicate)= 3.2 ± 0.5, and Rin(silicate)= 4.6 ± 0.2 RPhot. Our data did not show evidence of intra-cycle and cycle-to-cycle variability or of asymmetries within the error-bars and within the limits of our baseline and phase coverage.
Conclusions: Our model fits constrain the chemical composition and the inner boundary radii of the dust shells, as well as the photospheric angular diameters. Our interferometric results are consistent with Al2O3 grains condensing close to the stellar surface at about 2 stellar radii, co-located with the extended atmosphere and SiO maser emission, and warm silicate grains at larger distances of about 4-5 stellar radii. We verified that the number densities of aluminum can match that of the best-fit Al2O3 dust shell near the inner dust radius in sufficiently extended atmospheres, confirming that Al2O3 grains can be seed particles for the further dust condensation. Together with literature data of the mass-loss rates, our sample is consistent with a hypothesis that stars with low mass-loss rates form primarily dust that preserves the spectral properties of Al2O3, and stars with higher mass-loss rate form dust with properties of warm silicates.

Based on observations made with the Very Large Telescope Interferometer (VLTI) at the Paranal Observatory under program IDs 073.D-0711, 075.D-0097, 077.D-0630, 079.D-0172, and 082.D-0723.Tables 1-3, 8, 9 are available in electronic form at http://www.aanda.org Title: Mid-infrared interferometric observations of four oxygen-rich Mira variables Authors: Karovicova, I.; Wittkowski, M.; Ohnaka, K.; Boboltz, D. A.; Fossat, E.; Scholz, M. Bibcode: 2013EAS....63..191K Altcode: We present an investigation of the dust formation process in the atmospheres of the oxygen-rich AGB stars RR Aql, S Ori, GX Mon and R Cnc using spatially and spectrally resolved mid-infrared interferometric observations. We successfully compared multi epoch observations to a radiative transfer model of the dust shells, where the central stellar intensity profile is described by a series of dust-free dynamic model atmospheres based on self-excited pulsation models. We show that the Al2O3 shells have inner radii between 1.9 and 2.2 stellar photospheric radii, and that the silicate shells have inner radii between 4.1 and 4.6 stellar photospheric radii. The best-fit photospheric angular diameters are consistent with independent estimates. The model dust temperatures at the inner radii of 1.9-2.2 stellar radii and 4.1-4.6 stellar radii are consistent with dust condensation temperatures of Al2O3 and silicates, respectively. Title: Dome C site testing: long term statistics of integrated optical turbulence parameters at ground level Authors: Aristidi, E.; Agabi, A.; Fossat, E.; Ziad, A.; Abe, L.; Bondoux, E.; Bouchez, G.; Challita, Z.; Jeanneaux, F.; Mékarnia, D.; Petermann, D.; Pouzenc, C. Bibcode: 2013IAUS..288..300A Altcode: We present long term site testing statistics based on DIMM and GSM data obtained at Dome C, Antarctica. These data have been collected on the bright star Canopus since the end of 2003. We give values of the integrated turbulence parameters in the visible (wavelength 500 nm). The median value we obtained for the seeing are 1.2 arcsec, 2.0 arcsec and 0.8 arcsec at respective elevations of 8m, 3m and 20m above the ground. The isoplanatic angle median value is 4.0 arcsec and the median outer scale is 7.5m. We found that both the seeing and the isoplanatic angle exhibit a strong dependence with the season (the seeing is larger in winter while the isoplanatic angle is smaller). Title: Site testing for submillimetre astronomy at Dome C, Antarctica Authors: Tremblin, P.; Minier, V.; Schneider, N.; Durand, G. Al.; Ashley, M. C. B.; Lawrence, J. S.; Luong-van, D. M.; Storey, J. W. V.; Durand, G. An.; Reinert, Y.; Veyssiere, C.; Walter, C.; Ade, P.; Calisse, P. G.; Challita, Z.; Fossat, E.; Sabbatini, L.; Pellegrini, A.; Ricaud, P.; Urban, J. Bibcode: 2011A&A...535A.112T Altcode: 2011arXiv1110.4311T
Aims: Over the past few years a major effort has been put into the exploration of potential sites for the deployment of submillimetre astronomical facilities. Amongst the most important sites are Dome C and Dome A on the Antarctic Plateau, and the Chajnantor area in Chile. In this context, we report on measurements of the sky opacity at 200 μm over a period of three years at the French-Italian station, Concordia, at Dome C, Antarctica. We also present some solutions to the challenges of operating in the harsh polar environment.
Methods: The 200-μm atmospheric opacity was measured with a tipper. The forward atmospheric model MOLIERE (Microwave Observation LIne Estimation and REtrieval) was used to calculate the atmospheric transmission and to evaluate the precipitable water vapour content (PWV) from the observed sky opacity. These results have been compared with satellite measurements from the Infrared Atmospheric Sounding Interferometer (IASI) on Metop-A, with balloon humidity sondes and with results obtained by a ground-based microwave radiometer (HAMSTRAD). In addition, a series of experiments has been designed to study frost formation on surfaces, and the temporal and spatial evolution of thermal gradients in the low atmosphere.
Results: Dome C offers exceptional conditions in terms of absolute atmospheric transmission and stability for submillimetre astronomy. Over the austral winter the PWV exhibits long periods during which it is stable and at a very low level (0.1 to 0.3 mm). Higher values (0.2 to 0.8 mm) of PWV are observed during the short summer period. Based on observations over three years, a transmission of around 50% at 350 μm is achieved for 75% of the time. The 200-μm window opens with a typical transmission of 10% to 15% for 25% of the time.
Conclusions: Dome C is one of the best accessible sites on Earth for submillimetre astronomy. Observations at 350 or 450 μm are possible all year round, and the 200-μm window opens long enough and with a sufficient transparency to be useful. Although the polar environment severely constrains hardware design, a permanent observatory with appropriate technical capabilities is feasible. Because of the very good astronomical conditions, high angular resolution and time series (multi-year) observations at Dome C with a medium size single dish telescope would enable unique studies to be conducted, some of which are not otherwise feasible even from space. Title: Multi-Epoch Mid-Infrared Interferometric Observations of the Oxygen-rich Mira Variable Star RR Aql with the VLTI/MIDI Instrument Authors: Karovicova, I.; Wittkowski, M.; Boboltz, D. A.; Fossat, E.; Ohnaka, K.; Scholz, M. Bibcode: 2011ASPC..445..269K Altcode: This work is part of an on-going program of multi-epoch simultaneous observations of a sample of four evolved stars — RR Aql, GX Mon, S Ori, and AH Sco — using the VLTI and VLBA facilities. Different pulsating layers and their relative positions are monitored across phases and cycles. Here, we present mid-infrared interferometric observations of the oxygen-rich Mira variable RR Aql at 13 epochs covering 4 pulsation cycles with the MIDI instrument at the VLTI. We modeled the observed data using dust-free self-excited dynamic model atmospheres combined with an ad-hoc radiative transfer model of the dust shell. This study represents the first comparison between interferometric observations and dynamic models over an extended range of pulsation phases covering several cycles. We show that the combination of the models describe the observed data well. We determine the best dust-free dynamical model atmosphere and the best dust shell parameters including the optical depth of the two examined dust species (Al2O3 and silicates), the inner boundary radii of the dust shells, the density distribution, and the continuum photospheric angular diameter for all epochs. The results indicate that silicate is the major chemical component in the dust shell. We also compare the data with equivalent uniform disk (UD) and Gaussian FWHM diameters. Title: Molecular and Dusty Layers of Asymptotic Giant Branch Stars Studied with the VLT Interferometer Authors: Wittkowski, M.; Karovicova, I.; Boboltz, D. A.; Fossat, E.; Ireland, M.; Ohnaka, K.; Scholz, M.; van Wyk, F.; Whitelock, P.; Wood, P. R.; Zijlstra, A. A. Bibcode: 2011Msngr.145...24W Altcode: Mass loss from asymptotic giant branch (AGB) stars is the most important driver for the evolution of low to intermediate mass stars towards planetary nebulae. It is also one of the most important sources of chemical enrichment of the interstellar medium. The mass-loss process originates in the extended atmosphere, whose structure is affected by stellar pulsations, and where molecular and dusty layers are formed. Optical interferometry resolves the extended atmospheres of AGB stars and thereby enables us to obtain measurements of the intensity profile across this region. We present an overview of recent results from our spectro-interferometric observations of AGB stars using the near- and mid-infrared instruments AMBER and MIDI of the VLT Interferometer. Title: Mid-infrared interferometric monitoring of evolved stars. The dust shell around the Mira variable RR Aquilae at 13 epochs Authors: Karovicova, I.; Wittkowski, M.; Boboltz, D. A.; Fossat, E.; Ohnaka, K.; Scholz, M. Bibcode: 2011A&A...532A.134K Altcode: 2011arXiv1107.0909K
Aims: We present a unique multi-epoch infrared interferometric study of the oxygen-rich Mira variable RR Aql in comparison to radiative transfer models of the dust shell. We investigate flux and visibility spectra at 8-13 μm with the aim of better understanding the pulsation mechanism and its connection to the dust condensation sequence and mass-loss process.
Methods: We obtained 13 epochs of mid-infrared interferometry with the MIDI instrument at the VLTI between April 2004 and July 2007, covering minimum to pre-maximum pulsation phases (0.45-0.85) within four cycles. The data are modeled with a radiative transfer model of the dust shell where the central stellar intensity profile is described by a series of dust-free dynamic model atmospheres based on self-excited pulsation models. We examined two dust species, silicate and Al2O3 grains. We performed model simulations using variations in model phase and dust shell parameters to investigate the expected variability of our mid-infrared photometric and interferometric data.
Results: The observed visibility spectra do not show any indication of variations as a function of pulsation phase and cycle. The observed photometry spectra may indicate intracycle and cycle-to-cycle variations at the level of 1-2 standard deviations. The photometric and visibility spectra of RR Aql can be described well by the radiative transfer model of the dust shell that uses a dynamic model atmosphere describing the central source. The best-fitting model for our average pulsation phase of overline{Φ_V=0.64±0.15} includes the dynamic model atmosphere M21n (Tmodel = 2550 K) with a photospheric angular diameter of θPhot = 7.6 ± 0.6 mas, and a silicate dust shell with an optical depth of τV = 2.8 ± 0.8, an inner radius of Rin = 4.1 ± 0.7 RPhot, and a power-law index of the density distribution of p = 2.6 ± 0.3. The addition of an Al2O3 dust shell did not improve the model fit. However, our model simulations indicate that the presence of an inner Al2O3 dust shell with lower optical depth than for the silicate dust shell can not be excluded. The photospheric angular diameter corresponds to a radius of R_phot=520+230-140 R_⊙ and an effective temperature of Teff 2420 ± 200 K. Our modeling simulations confirm that significant intracycle and cycle-to-cycle visibility variations are not expected for RR Aql at mid-infrared wavelengths within our uncertainties. Conclusions: We conclude that our RR Aql data can be described by a pulsating atmosphere surrounded by a silicate dust shell. The effects of the pulsation on the mid-infrared flux and visibility values are expected to be less than about 25% and 20%, respectively, and are too low to be detected within our measurement uncertainties.

Based on observations made with Very Large Telescope Interferometer (VLTI) at the Paranal Observatory under program IDs 073.D-0711, 075.D-0097, 077.D-0630, and 079.D-0172.Figure 5 is available in electronic form at http://www.aanda.org Title: Some results after 10 years of site testing at Concordia, Antarctica Authors: Fossat, Eric Bibcode: 2011arXiv1101.3210F Altcode: At an altitude of 3250m and at a latitude of $75^\circ$S, the Italo-French Concordia station was open to winter-over teams in 2005. It is one of the high points of the Antarctic polar plateau. These extreme remote sites are expected to provide exceptional conditions for astronomical observations, specially in the infra-red ranges, given the very cold winter temperatures, averaging well below -60C. Being very flat as highest points of that very broad polar plateau, they are also not subject to the famous katabatic winds that can be devastating on the Antarctic coast, and in fact their mean wind speed along the year are the weakest known on Earth, less than 3 m/s. Besides the resulting absence of danger that such winds would present for large size optical instruments, this situation offers another benefit, which is an excellent free atmosphere seeing above a very thin but turbulent surface layer. This paper emphasizes these seeing peculiarities, but not only. It is presented as simply following a significant fraction of my slide presentation during the meeting. Title: Typical duration of good seeing sequences at Concordia Authors: Fossat, E.; Aristidi, E.; Agabi, A.; Bondoux, E.; Challita, Z.; Jeanneaux, F.; Mékarnia, D. Bibcode: 2010A&A...517A..69F Altcode: 2010arXiv1003.3583F Context. The winter seeing at Concordia is bimodal, i.e. either excellent or quite poor, depending on the altitude above the snow surface. We study the temporal behavior of the good seeing sequences. Efficient exploitation of extremely good seeing conditions with an adaptive optics system requires long integrations.
Aims: We examine the temporal distribution of time intervals providing excellent seeing at Concordia.
Methods: We create temporal windows of good seeing by applying a simple binary process: good or bad. We correct the autocorrelations of these windows for those of the existing data sets, since these are not continuous, often being interrupted by technical problems in addition to the adverse weather gaps. We infer the typical duration of good seeing sequences from these corrected autocorrelations. This study has to be a little detailed as its results depend on the season, summer or winter.
Results: When we adopt a threshold of 0.5 arcsec to define “good seeing”, we find that three characteristic numbers describe the temporal evolution of the good seeing windows. The first number is the mean duration of an uninterrupted good seeing sequence, which is τ0 = 7.5 h at 8 m above the ground and 15 h at 20 m. These sequences are randomly distributed in time, following a negative exponential law of damping time τ1 = 29 h (at elevation 8 m and 20 m), which represents our second number. The third number is the mean time between two 29 h episodes, which is T = 10 days at 8 m high (5 days at 20 m).
Conclusions: There is certainly no other site on Earth, except for the few other high altitude Domes on the Antarctic plateau, at which we can achieve these exceptionally high quality seeing conditions. Title: Studying the vertical extent of the ground layer turbulence using sonic-anemometers Authors: Travouillon, T.; Aristidi, E.; Fossat, E.; Bondoux, E.; Challita, Z.; Mekarnia, D.; Jeanneaux, F.; Odoardi, D.; Lawrence, J. S. Bibcode: 2010EAS....40..115T Altcode: The optical turbulence above Dome C in winter is mainly concentrated in the first tens of meters above the ground. The properties of this so-called surface layer were investigated during the last two winterover by a set of sonics anemometers placed on a 45 m high tower. These anemometers provide measurements of the temperature and the wind speed vector. The sampling rate of 10 Hz allows to derivate the refractive index structure constant C_n^2. We report here the first analysis of these data. Title: Dome C boundary layer and seeing peculiarities Authors: Fossat, E.; Aristidi, E.; Astroconcordia Team Bibcode: 2010EAS....40...73F Altcode: This paper presents some statistical information about the Concordia turbulent surface inversion layer, regarding height and turbulent energy, its contribution to the peculiar local seeing, and the free atmosphere seeing encountered just above this surface layer. Title: Implications of Turbulence Optical Parameters on HAR Techniques at Dome C Authors: Ziad, A.; Aristidi, E.; Agabi, A.; Fossat, E.; Borgnino, J.; Maire, J.; Martin, F. Bibcode: 2010EAS....40...21Z Altcode: The HAR observing methods such as Adaptive Optics and Interferometery, require a better understanding of the behavior of the perturbed wavefronts, more exactly a better knowledge of the atmospheric turbulence model in addition to the associate parameters. This is very crucial for modeling the HAR techniques and particularly for the evaluation of their performance. Indeed, it is well-known that the performance of an AO system depends upon the seeing conditions, the outer scale, the isoplanatic angle and the coherence time. A review of the site-testing instruments deployed at Dome C will be given, their pertinence and their implications on HAR techniques will be discussed comparatively to the Paranal site. Title: Dome C site testing: surface layer, free atmosphere seeing, and isoplanatic angle statistics Authors: Aristidi, E.; Fossat, E.; Agabi, A.; Mékarnia, D.; Jeanneaux, F.; Bondoux, E.; Challita, Z.; Ziad, A.; Vernin, J.; Trinquet, H. Bibcode: 2009A&A...499..955A Altcode: 2009arXiv0904.2982A This paper analyses 3 1/2 years of site testing data obtained at Dome C, Antarctica, based on measurements obtained with three DIMMs located at three different elevations. Basic statistics of the seeing and the isoplanatic angle are given, as well as the characteristic time of temporal fluctuations of these two parameters, which we found to around 30 min at 8 m. The 3 DIMMs are exploited as a profiler of the surface layer, and provide a robust estimation of its statistical properties. It appears to have a very sharp upper limit (less than 1 m). The fraction of time spent by each telescope above the top of the surface layer permits us to deduce a median height of between 23 m and 27 m. The comparison of the different data sets led us to infer the statistical properties of the free atmosphere seeing, with a median value of 0.36 arcsec. The C_n2 profile inside the surface layer is also deduced from the seeing data obtained during the fraction of time spent by the 3 telescopes inside this turbulence. Statistically, the surface layer, except during the 3-month summer season, contributes to 95 percent of the total turbulence from the surface level, thus confirming the exceptional quality of the site above it. Title: First statistics of the turbulence outer scale at Dome C Authors: Ziad, A.; Aristidi, E.; Agabi, A.; Borgnino, J.; Martin, F.; Fossat, E. Bibcode: 2008A&A...491..917Z Altcode: Context: The outer scale of wavefronts is of interest for the dimensioning and the optimisation of the High Angular Resolution techniques such as Interferometry and Adaptive Optics, particularly for the new generation of telescopes such as the Extremely Large Telescopes (ELT).
Aims: We aim to provide the first statistics of the outer scale at Dome C site in Antarctica to finalize the characterization of this site.
Methods: A new version of the Generalized Seeing Monitor has been developed for extremely cold conditions. Two DIMMs (Differential Image Motion Monitor) were coupled to extract Angle-of-Arrival (AA) fluctuations using CCD detectors. Correlations of these AA fluctuations for different baselines lead to outer scale estimations.
Results: For the first time, statistics of the outer scale at Dome C are provided leading to small values in the surface layer at Dome C. These small outer scale values compared to temperate sites considerably reduce the fringe excursion of interferometers and the low orders of the normalized amplitude of atmospheric Zernike coefficients, particularly the tip-tilt.
Conclusions: The Dome C small outer scale combined with the large coherence time and large isoplanatic angle are very useful for the development of Adaptive Optics systems and long-baseline interferometers. Title: SYMPA, a dedicated instrument for Jovian seismology. II. Real performance and first results Authors: Gaulme, P.; Schmider, F. X.; Gay, J.; Jacob, C.; Alvarez, M.; Reyes-Ruiz, M.; Belmonte, J. A.; Fossat, E.; Jeanneaux, F.; Valtier, J. -C. Bibcode: 2008A&A...490..859G Altcode: 2008arXiv0802.1777G Aims: SYMPA is the first instrument dedicated to the observation of free oscillations of Jupiter. Its principles and theoretical performance have been presented in Paper I. This second paper describes the data processing method, the real instrumental performance and presents the first results of a Jovian observation run, lead in 2005 at Teide Observatory.
Methods: SYMPA is a Fourier transform spectrometer which works at a fixed optical path difference. It produces Doppler shift maps of the observed object. The velocity amplitude of Jupiter's oscillations is expected to be below 60 cm s-1.
Results: Despite light technical defects, the instrument was demonstrated to work correctly, being limited only by photon noise. A noise level of about 12 cm s-1 was reached on a 10-night observation run, with 21% duty cycle, which is 5 time better than similar previous observations. However, no signal from Jupiter is clearly highlighted. Title: Optical turbulence and outer scales above Dome C in Antarctica Authors: Trinquet, Hervé; Agabi, Abdelkrim; Vernin, Jean; Azouit, Max; Aristidi, Eric; Fossat, Eric Bibcode: 2008SPIE.7012E..25T Altcode: 2008SPIE.7012E..75T Dome C in Antarctica is a particular astronomical site when considering the optical turbulence conditions. From the first winterover campaign performed in 2005 at Dome C, the set of 34 meteorological balloon profiles has been analyzed. The meteorological balloons were equipped with microthermal sensors used to sense the vertical profile of the optical turbulence intensity C2n. The C2n median profile, mean temperature and mean horizontal wind speed are given. The C2n median profile is characterized by a very strong and thin turbulent surface layer. The surface layer height is defined. The median outer scale profile at Dome C is computed using the Tatarski definition. The von Karman outer scale is also deduced. The integrated parameters as Fried parameter r0, coherence time τ0, isoplanatic angle θ0 and the spatial-coherence outer scale L0 used to define astronomical site quality, are computed at 8 m above the ground and above the turbulent surface layer. Title: IRAN: laboratory test bench for hypertelescope pupil-plane recombination Authors: Allouche, F.; Vakili, F.; Glindemann, A.; Aristidi, E.; Abe, L.; Fossat, E.; Douet, R. Bibcode: 2008SPIE.7013E..3TA Altcode: 2008SPIE.7013E.117A In 2004, our group proposed IRAN, an alternative beam-combination technique to the so-called hypertelescope imaging method introduced by Labeyrie in the 1990s. We have recently set up a laboratory experiment aiming at validating our image densification approach instead of the pupil densification scheme of Labeyrie. In our experiment, seven sub-apertures illuminated by laser sources are recombined using the IRAN scheme. The validation of the IRAN recombination consists basically in retrieving the point-spread intensity distribution (PSID), demonstrating the conservation of the object-image convolution relation. We will introduce IRAN, compare it to the hyper-telescope, and present the experimental results that we obtained. Title: Sampling the ground layer of the atmosphere at Dome C using fast sonic-anemometers Authors: Travouillon, T.; Aristidi, E.; Fossat, E.; Lawrence, J. S.; Mekarnia, D.; Moore, A. M.; Skidmore, A. W.; Storey, J. W. V. Bibcode: 2008SPIE.7012E..4BT Altcode: 2008SPIE.7012E.147T The ground layer turbulence at Dome C is the cause for more than 90% of the total turbulence column. While the height of this layer has been currently measured to be approximately 30m, no long term statistics is available from this part of the atmosphere. In order to plan the construction of future telescope at this site temperature site, temperature, wind speed and turbulence measurements are also necessary. Using fast sonicanemometers we present, a preliminary set of data covering January to October 2007 sampling these quantities at heights of 8, 16 and 28 meters. Title: Nighttime Optical Turbulence Vertical Structure above Dome C in Antarctica Authors: Trinquet, Hervé; Agabi, Abdelkrim; Vernin, Jean; Azouit, Max; Aristidi, Eric; Fossat, Eric Bibcode: 2008PASP..120..203T Altcode: During the austral winter 2005, the first astronomical site testing campaign were performed at Dome C, in Antarctica. Thirty-five meteorological balloons equipped with microthermal sensors were used to sense the vertical profile of the optical turbulence intensity above Dome C up to 20 km. All the profiles of the 2005 campaign are statistically analyzed. We provide the median profiles and the mean potential temperature, mean horizontal wind speed, and mean direction profiles for the three seasons covered by this campaign (autumn, winter, and beginning of the spring). The structure of the optical turbulence in the atmosphere above Dome C is analyzed and compared with the well-known median profiles of midlatitude sites. Of the whole optical turbulence, 80% lies within the first 33 m above the ground and 9% in the upper part of the boundary layer, between 33 m and 1 km above the ground. The remaining 11% are in the free atmosphere. This is an extreme situation when compared with “classical” midlatitude sites where the surface layer extends up to 200 m. This strong and thin surface layer is the result of the kinetic turbulent mixing of air combined with a strong potential temperature gradient. The site is characterized from the adaptive optics point of view. Seeing, isoplanatic angle, and coherence time are estimated for each considered seasons. A four-layer decomposition for each season is provided for adaptive optics simulations. For high angular astronomy, a telescope at Dome C needs to be elevated over this surface layer, or a specific GLAO needs to be designed. Combined with the unique possibility of performing continuous observation from Antarctica, scientific programs such as microlensing, pulsating stars, and asteroseismology become feasible. Title: Dome C site testing results Authors: Fossat, E. Bibcode: 2008EAS....33....5F Altcode: The first site testing campaigns started at Dome C during the summer season 2000 2001. Since then, each further summer has been exploited, as well as the first three winter seasons permitted by the opening of the Concordia station in 2005. Many of the astronomical site properties begin now to be well known, although some more still need to be adressed and more statistics is obviously required. Title: Inter-Division Ix-X / Working Group Encouraging the International Development of Antarctic Astronomy Authors: Burton, Michael G.; Busso, Maurizio; Fossat, Eric G.; Lloyd, James P.; McCaughrean, Mark J.; Spiering, Christian; Tori, Shoji Bibcode: 2007IAUTB..26..188B Altcode: The business session of the Working Group followed the completion of Special Session 7, Astronomy in Antarctica. The proceedings of this meeting are published in Highlights in Astronomy, Volume 14 (Ed. K. A. van der Hucht, 2007, CUP). The session involved 18 papers spread over 5 sessions, together with a further 18 poster papers. A dinner was also held in Prague following the first day of the Special Session. Title: SYMPA, a dedicated instrument for Jovian seismology. I. Principle and performance Authors: Schmider, F. X.; Gay, J.; Gaulme, P.; Jacob, C.; Abe, L.; Alvarez, M.; Belmonte, J. A.; Fossat, E.; Gelly, B.; Guillot, T.; Jeanneaux, F.; Mosser, B.; Valtier, J. -C. Bibcode: 2007A&A...474.1073S Altcode: Aims:The detection and measurement of acoustic modes on the giant planets of the solar system is of great interest for the study of the internal structure and evolution of the giant planets, as well as the study of the solar system formation. Such observations require a dedicated instrument and observing procedure.
Methods: We describe the principle and the performance of an instrument dedicated to seismology of giant planets. In this first paper, we describe the principle and the optical scheme, and derive the theoretical performances. As for the Sun, it is possible to measure modes with spatial resolution, but a larger collecting area is necessary. As for asteroseismology in general, continuity in the observation is also required.
Results: From results obtained at the laboratory, we derive the actual performance of the instrument and estimate its capabilities in network observations.
Conclusions: We demonstrate that the proposed instrument and strategy is adapted for the seismology of giant planets. In a second paper, we will present the first data set obtained with it, explain the data reduction procedure, and present preliminary results. Title: Site testing at Dome C: history and present status Authors: Vernin, Jean; Agabi, Abdelkrim; Aristidi, Eric; Azouit, Max; Chadid, Merieme; Fossat, Eric; Sadibekova, Tatiana; Trinquet, Hervé; Ziad, Aziz Bibcode: 2007HiA....14..693V Altcode: The idea of starting an astronomical site testing in Antarctica began during a congress organized by French Académie des Sciences, in 1992, and entitled ‘Recherches polaires-Une Stratégie pour l'an 2000’. At this time, one of us (Vernin 1994) gave a proposal for an astronomical site testing in Antarctica. This proposal was rapidly followed by a meeting between Al Harper (from ‘Center for Astrophysical Research in Antarctica’, Chicago), Peter Gillingham (from the Anglo Australian Observatory, Australia) and Jean Vernin (from Nice University) at Lake Geneva, Wisconsin, in 1993. It was decided to investigate what was the astronomical quality of South Pole station, each institute bringing its own participation: CARA, the South Pole infrastructure, University of New South Wales, a PhD student and Nice University its expertise and instruments. Title: Multi-aperture interferometry at Concordia Authors: Fossat, Eric; Vakili, Farrokh; Aristidi, Eric; Lopez, Bruno; Schmider, François-Xavier; Agabi, Karim; Daban, Jean-Baptiste; Allouche, Fatmé; Belu, Adrian; Gori, Pierre-Marie; Guerri, Géraldine; Valat, Bruno Bibcode: 2007HiA....14..705F Altcode: The next generation (post-VLTI) of multi-telescope interferometric arrays operated in optical/infrared wavelengths should be kilometric, from 1 to 10 km. The Concordia station offers a unique opportunity to set such an interferometer in the best atmospheric conditions presently known on Earth. Title: Atmospheric scintillation at Dome C, Antarctica Authors: Kenyon, Suzanne L.; Lawrence, Jon S.; Ashley, Michael C. B.; Storey, John W. V.; Tokovinin, Andrei; Fossat, Eric Bibcode: 2007HiA....14..698K Altcode: Dome C, Antarctica is one of the most promising astronomical sites in the world (Fossat & Candidi 2003, and references therein). Dome C boasts low wind speeds, very cold temperatures and little precipitation. The atmospheric turbulence is very weak compared to temperate sites, leading to sub-arcsecond seeing conditions (Lawrence et al. 2004; Agabi et al. 2006). Title: Asteroseismology at Dome C in Antarctica Authors: Fossat, Eric Bibcode: 2007CoAst.150..307F Altcode: The Antarctica plateau, at altitudes between 3 and 4 kilometres, offers the best possible sky for many astronomical purposes. Among these are the need for an excellent sky transparency, a heavily reduced level of scintillation and the possibility of very long times of integration only interrupted by rare clouds. So, asteroseismology observations using both photometry and spectroscopy are among the first scientific targets for the next few years at the Italo-French Concordia station, that is now open for winter-over activity since February, 2005. I briefly described the site testing activity and what we already know of the sky quality, and then the asteroseismic programmes that are likely to start within the next 5 years or so. Title: Jovian seismology: preliminary results of the SYMPA instrument Authors: Gaulme, P.; Schmider, F. X.; Gay, J.; Jacob, C.; Jeanneaux, F.; Fossat, E.; Valtier, J. C.; Alvarez, M.; Reyes, M. Bibcode: 2007CoAst.150..313G Altcode: Jupiter's internal structure is poorly known (Guillot et al. 1997). Seismology is a powerful tool to investigate the internal structure of planets and stars, by analysing how acoustic waves propagate. Mosser (1997) and Gudkova & Zarkhov (1999) showed that the detection and the identification of non-radial modes up to degree ℓ=25 can constrain strongly the internal structure. SYMPA is a ground-based network project dedicated to the Jovian oscillations (Schmider et al. 2002). The instrument is composed of a Mach-Zehnder interferometer which produces four interferograms of the planetary spectrum. The combination of the four images in phase quadrature allows the reconstruction of the incident light phase, which is related to the Doppler shift generated by the oscillations. Two SYMPA instruments were built at the Nice university and were used simultaneously during two observation campaigns, in 2004 and 2005, at the San Pedro Martir Observatory (Mexico) and the Izana Observatory (Las Canarias). We present for the first time the data processing and the preliminary results of the experiment. Title: Astronomy at Dome C: an overview Authors: Fossat, Eric Bibcode: 2007sfaa.confE...6F Altcode: No abstract at ADS Title: AMBER, the near-infrared spectro-interferometric three-telescope VLTI instrument Authors: Petrov, R. G.; Malbet, F.; Weigelt, G.; Antonelli, P.; Beckmann, U.; Bresson, Y.; Chelli, A.; Dugué, M.; Duvert, G.; Gennari, S.; Glück, L.; Kern, P.; Lagarde, S.; Le Coarer, E.; Lisi, F.; Millour, F.; Perraut, K.; Puget, P.; Rantakyrö, F.; Robbe-Dubois, S.; Roussel, A.; Salinari, P.; Tatulli, E.; Zins, G.; Accardo, M.; Acke, B.; Agabi, K.; Altariba, E.; Arezki, B.; Aristidi, E.; Baffa, C.; Behrend, J.; Blöcker, T.; Bonhomme, S.; Busoni, S.; Cassaing, F.; Clausse, J. -M.; Colin, J.; Connot, C.; Delboulbé, A.; Domiciano de Souza, A.; Driebe, T.; Feautrier, P.; Ferruzzi, D.; Forveille, T.; Fossat, E.; Foy, R.; Fraix-Burnet, D.; Gallardo, A.; Giani, E.; Gil, C.; Glentzlin, A.; Heiden, M.; Heininger, M.; Hernandez Utrera, O.; Hofmann, K. -H.; Kamm, D.; Kiekebusch, M.; Kraus, S.; Le Contel, D.; Le Contel, J. -M.; Lesourd, T.; Lopez, B.; Lopez, M.; Magnard, Y.; Marconi, A.; Mars, G.; Martinot-Lagarde, G.; Mathias, P.; Mège, P.; Monin, J. -L.; Mouillet, D.; Mourard, D.; Nussbaum, E.; Ohnaka, K.; Pacheco, J.; Perrier, C.; Rabbia, Y.; Rebattu, S.; Reynaud, F.; Richichi, A.; Robini, A.; Sacchettini, M.; Schertl, D.; Schöller, M.; Solscheid, W.; Spang, A.; Stee, P.; Stefanini, P.; Tallon, M.; Tallon-Bosc, I.; Tasso, D.; Testi, L.; Vakili, F.; von der Lühe, O.; Valtier, J. -C.; Vannier, M.; Ventura, N. Bibcode: 2007A&A...464....1P Altcode: Context: Optical long-baseline interferometry is moving a crucial step forward with the advent of general-user scientific instruments that equip large aperture and hectometric baseline facilities, such as the Very Large Telescope Interferometer (VLTI).
Aims: AMBER is one of the VLTI instruments that combines up to three beams with low, moderate and high spectral resolutions in order to provide milli-arcsecond spatial resolution for compact astrophysical sources in the near-infrared wavelength domain. Its main specifications are based on three key programs on young stellar objects, active galactic nuclei central regions, masses, and spectra of hot extra-solar planets.
Methods: These key science goals led to scientific specifications, which were used to propose and then validate the instrument concept. AMBER uses single-mode fibers to filter the entrance signal and to reach highly accurate, multiaxial three-beam combination, yielding three baselines and a closure phase, three spectral dispersive elements, and specific self-calibration procedures.
Results: The AMBER measurements yield spectrally dispersed calibrated visibilities, color-differential complex visibilities, and a closure phase allows astronomers to contemplate rudimentary imaging and highly accurate visibility and phase differential measurements. AMBER was installed in 2004 at the Paranal Observatory. We describe here the present implementation of the instrument in the configuration with which the astronomical community can access it.
Conclusions: .After two years of commissioning tests and preliminary observations, AMBER has produced its first refereed publications, allowing assessment of its scientific potential. Title: An asymmetry detected in the disk of κ Canis Majoris with AMBER/VLTI Authors: Meilland, A.; Millour, F.; Stee, P.; Domiciano de Souza, A.; Petrov, R. G.; Mourard, D.; Jankov, S.; Robbe-Dubois, S.; Spang, A.; Aristidi, E.; Antonelli, P.; Beckmann, U.; Bresson, Y.; Chelli, A.; Dugué, M.; Duvert, G.; Gennari, S.; Glück, L.; Kern, P.; Lagarde, S.; Le Coarer, E.; Lisi, F.; Malbet, F.; Perraut, K.; Puget, P.; Rantakyrö, F.; Roussel, A.; Tatulli, E.; Weigelt, G.; Zins, G.; Accardo, M.; Acke, B.; Agabi, K.; Altariba, E.; Arezki, B.; Baffa, C.; Behrend, J.; Blöcker, T.; Bonhomme, S.; Busoni, S.; Cassaing, F.; Clausse, J. -M.; Colin, J.; Connot, C.; Delboulbé, A.; Driebe, T.; Feautrier, P.; Ferruzzi, D.; Forveille, T.; Fossat, E.; Foy, R.; Fraix-Burnet, D.; Gallardo, A.; Giani, E.; Gil, C.; Glentzlin, A.; Heiden, M.; Heininger, M.; Hernandez Utrera, O.; Hofmann, K. -H.; Kamm, D.; Kiekebusch, M.; Kraus, S.; Le Contel, D.; Le Contel, J. -M.; Lesourd, T.; Lopez, B.; Lopez, M.; Magnard, Y.; Marconi, A.; Mars, G.; Martinot-Lagarde, G.; Mathias, P.; Mège, P.; Monin, J. -L.; Mouillet, D.; Nussbaum, E.; Ohnaka, K.; Pacheco, J.; Perrier, C.; Rabbia, Y.; Rebattu, S.; Reynaud, F.; Richichi, A.; Robini, A.; Sacchettini, M.; Schertl, D.; Schöller, M.; Solscheid, W.; Stefanini, P.; Tallon, M.; Tallon-Bosc, I.; Tasso, D.; Testi, L.; Vakili, F.; von der Lühe, O.; Valtier, J. -C.; Vannier, M.; Ventura, N. Bibcode: 2007A&A...464...73M Altcode: 2006astro.ph.11563M Aims:We study the geometry and kinematics of the circumstellar environment of the Be star κ CMa in the Brγ emission line and its nearby continuum.
Methods: We use the AMBER/VLTI instrument operating in the K band, which provides a spatial resolution of about 6 mas with a spectral resolution of 1500, to study the kinematics within the disk and to infer its rotation law. To obtain more kinematical constraints we also use a high spectral resolution Paβ line profile obtain in December 2005 at the Observatorio do Pico do Dios, Brazil and we compile V/R line profile variations and spectral energy distribution data points from the literature.
Results: Using differential visibilities and differential phases across the Brγ line we detect an asymmetry in the disk. Moreover, we found that κ CMa seems difficult to fit within the classical scenario for Be stars, illustrated recently by α Arae observations, i.e. a fast rotating B star close to its breakup velocity surrounded by a Keplerian circumstellar disk with an enhanced polar wind. We discuss the possibility that κ CMa is a critical rotator with a Keplerian rotating disk and examine whether if the detected asymmetry can be interpreted within the “one-armed” viscous disk framework.

Based on observations collected at the European Southern Observatory, Paranal, Chile, within the guaranteed time programme 074.A-9025(A). Title: Constraining the wind launching region in Herbig Ae stars: AMBER/VLTI spectroscopy of HD 104237 Authors: Tatulli, E.; Isella, A.; Natta, A.; Testi, L.; Marconi, A.; Malbet, F.; Stee, P.; Petrov, R. G.; Millour, F.; Chelli, A.; Duvert, G.; Antonelli, P.; Beckmann, U.; Bresson, Y.; Dugué, M.; Gennari, S.; Glück, L.; Kern, P.; Lagarde, S.; Le Coarer, E.; Lisi, F.; Perraut, K.; Puget, P.; Rantakyrö, F.; Robbe-Dubois, S.; Roussel, A.; Weigelt, G.; Zins, G.; Accardo, M.; Acke, B.; Agabi, K.; Altariba, E.; Arezki, B.; Aristidi, E.; Baffa, C.; Behrend, J.; Blöcker, T.; Bonhomme, S.; Busoni, S.; Cassaing, F.; Clausse, J. -M.; Colin, J.; Connot, C.; Delboulbé, A.; Domiciano de Souza, A.; Driebe, T.; Feautrier, P.; Ferruzzi, D.; Forveille, T.; Fossat, E.; Foy, R.; Fraix-Burnet, D.; Gallardo, A.; Giani, E.; Gil, C.; Glentzlin, A.; Heiden, M.; Heininger, M.; Hernandez Utrera, O.; Hofmann, K. -H.; Kamm, D.; Kiekebusch, M.; Kraus, S.; Le Contel, D.; Le Contel, J. -M.; Lesourd, T.; Lopez, B.; Lopez, M.; Magnard, Y.; Mars, G.; Martinot-Lagarde, G.; Mathias, P.; Mège, P.; Monin, J. -L.; Mouillet, D.; Mourard, D.; Nussbaum, E.; Ohnaka, K.; Pacheco, J.; Perrier, C.; Rabbia, Y.; Rebattu, S.; Reynaud, F.; Richichi, A.; Robini, A.; Sacchettini, M.; Schertl, D.; Schöller, M.; Solscheid, W.; Spang, A.; Stefanini, P.; Tallon, M.; Tallon-Bosc, I.; Tasso, D.; Vakili, F.; von der Lühe, O.; Valtier, J. -C.; Vannier, M.; Ventura, N. Bibcode: 2007A&A...464...55T Altcode: 2006astro.ph..6684T Aims:We investigate the origin of the Brγ emission of the Herbig Ae star HD 104237 on Astronomical Unit (AU) scales.
Methods: Using AMBER/VLTI at a spectral resolution R=1500 we spatially resolve the emission in both the Brγ line and the adjacent continuum.
Results: The visibility does not vary between the continuum and the Brγ line, even though the line is strongly detected in the spectrum, with a peak intensity 35% above the continuum. This demonstrates that the line and continuum emission have similar size scales. We assume that the K-band continuum excess originates in a “puffed-up” inner rim of the circumstellar disk, and discuss the likely origin of Brγ.
Conclusions: .We conclude that this emission most likely arises from a compact disk wind, launched from a region 0.2-0.5 AU from the star, with a spatial extent similar to that of the near infrared continuum emission region, i.e., very close to the inner rim location.

Based on observations collected at the European Southern Observatory, Paranal, Chile, within the guaranteed time programme 074.A-9025(A). Title: Disk and wind interaction in the young stellar object MWC 297 spatially resolved with AMBER/VLTI Authors: Malbet, F.; Benisty, M.; de Wit, W. -J.; Kraus, S.; Meilland, A.; Millour, F.; Tatulli, E.; Berger, J. -P.; Chesneau, O.; Hofmann, K. -H.; Isella, A.; Natta, A.; Petrov, R. G.; Preibisch, T.; Stee, P.; Testi, L.; Weigelt, G.; Antonelli, P.; Beckmann, U.; Bresson, Y.; Chelli, A.; Dugué, M.; Duvert, G.; Gennari, S.; Glück, L.; Kern, P.; Lagarde, S.; Le Coarer, E.; Lisi, F.; Perraut, K.; Puget, P.; Rantakyrö, F.; Robbe-Dubois, S.; Roussel, A.; Zins, G.; Accardo, M.; Acke, B.; Agabi, K.; Altariba, E.; Arezki, B.; Aristidi, E.; Baffa, C.; Behrend, J.; Blöcker, T.; Bonhomme, S.; Busoni, S.; Cassaing, F.; Clausse, J. -M.; Colin, J.; Connot, C.; Delboulbé, A.; Domiciano de Souza, A.; Driebe, T.; Feautrier, P.; Ferruzzi, D.; Forveille, T.; Fossat, E.; Foy, R.; Fraix-Burnet, D.; Gallardo, A.; Giani, E.; Gil, C.; Glentzlin, A.; Heiden, M.; Heininger, M.; Hernandez Utrera, O.; Kamm, D.; Kiekebusch, M.; Le Contel, D.; Le Contel, J. -M.; Lesourd, T.; Lopez, B.; Lopez, M.; Magnard, Y.; Marconi, A.; Mars, G.; Martinot-Lagarde, G.; Mathias, P.; Mège, P.; Monin, J. -L.; Mouillet, D.; Mourard, D.; Nussbaum, E.; Ohnaka, K.; Pacheco, J.; Perrier, C.; Rabbia, Y.; Rebattu, S.; Reynaud, F.; Richichi, A.; Robini, A.; Sacchettini, M.; Schertl, D.; Schöller, M.; Solscheid, W.; Spang, A.; Stefanini, P.; Tallon, M.; Tallon-Bosc, I.; Tasso, D.; Vakili, F.; von der Lühe, O.; Valtier, J. -C.; Vannier, M.; Ventura, N. Bibcode: 2007A&A...464...43M Altcode: 2005astro.ph.10350M The young stellar object MWC 297 is an embedded B1.5Ve star exhibiting strong hydrogen emission lines and a strong near-infrared continuum excess. This object has been observed with the VLT interferometer equipped with the AMBER instrument during its first commissioning run. AMBER/VLTI is currently the only near infrared interferometer that can observe spectrally dispersed visibilities. MWC 297 has been spatially resolved in the continuum with a visibility of 0.50+0.08-0.10 as well as in the Brγ emission line where the visibility decreases to 0.33±0.06. This change in the visibility with wavelength can be interpreted by the presence of an optically thick disk responsible for the visibility in the continuum and of a stellar wind traced by the Brγ emission line and whose apparent size is 40% larger. We validate this interpretation by building a model of the stellar environment that combines a geometrically thin, optically thick accretion disk model consisting of gas and dust, and a latitude-dependent stellar wind outflowing above the disk surface. The continuum emission and visibilities obtained from this model are fully consistent with the interferometric AMBER data. They agree also with existing optical, near-infrared spectra and other broad-band near-infrared interferometric visibilities. We also reproduce the shape of the visibilities in the Brγ line as well as the profile of this line obtained at an higher spectral resolution with the VLT/ISAAC spectrograph, and those of the Hα and Hβ lines. The disk and wind models yield a consistent inclination of the system of approximately 20°. A picture emerges in which MWC 297 is surrounded by an equatorial flat disk that is possibly still accreting and an outflowing wind that has a much higher velocity in the polar region than at the equator. The AMBER/VLTI unique capability of measuring spectral visibilities therefore allows us for the first time to compare the apparent geometry of a wind with the disk structure in a young stellar system.

Based on observations collected at the European Southern Observatory, Paranal, Chile, within the commissioning programme 60.A-9054(A). Title: Near-infrared interferometry of η Carinae with spectral resolutions of 1 500 and 12 000 using AMBER/VLTI Authors: Weigelt, G.; Kraus, S.; Driebe, T.; Petrov, R. G.; Hofmann, K. -H.; Millour, F.; Chesneau, O.; Schertl, D.; Malbet, F.; Hillier, J. D.; Gull, T.; Davidson, K.; Domiciano de Souza, A.; Antonelli, P.; Beckmann, U.; Bresson, Y.; Chelli, A.; Dugué, M.; Duvert, G.; Gennari, S.; Glück, L.; Kern, P.; Lagarde, S.; Le Coarer, E.; Lisi, F.; Perraut, K.; Puget, P.; Rantakyrö, F.; Robbe-Dubois, S.; Roussel, A.; Tatulli, E.; Zins, G.; Accardo, M.; Acke, B.; Agabi, K.; Altariba, E.; Arezki, B.; Aristidi, E.; Baffa, C.; Behrend, J.; Blöcker, T.; Bonhomme, S.; Busoni, S.; Cassaing, F.; Clausse, J. -M.; Colin, J.; Connot, C.; Delboulbé, A.; Feautrier, P.; Ferruzzi, D.; Forveille, T.; Fossat, E.; Foy, R.; Fraix-Burnet, D.; Gallardo, A.; Giani, E.; Gil, C.; Glentzlin, A.; Heiden, M.; Heininger, M.; Hernandez Utrera, O.; Kamm, D.; Kiekebusch, M.; Le Contel, D.; Le Contel, J. -M.; Lesourd, T.; Lopez, B.; Lopez, M.; Magnard, Y.; Marconi, A.; Mars, G.; Martinot-Lagarde, G.; Mathias, P.; Mège, P.; Monin, J. -L.; Mouillet, D.; Mourard, D.; Nussbaum, E.; Ohnaka, K.; Pacheco, J.; Perrier, C.; Rabbia, Y.; Rebattu, S.; Reynaud, F.; Richichi, A.; Robini, A.; Sacchettini, M.; Schöller, M.; Solscheid, W.; Spang, A.; Stee, P.; Stefanini, P.; Tallon, M.; Tallon-Bosc, I.; Tasso, D.; Testi, L.; Vakili, F.; von der Lühe, O.; Valtier, J. -C.; Vannier, M.; Ventura, N.; Weis, K.; Wittkowski, M. Bibcode: 2007A&A...464...87W Altcode: 2006astro.ph..9715W Aims: We present the first NIR spectro-interferometry of the LBV η Carinae. The observations were performed with the AMBER instrument of the ESO Very Large Telescope Interferometer (VLTI) using baselines from 42 to 89 m. The aim of this work is to study the wavelength dependence of η Car's optically thick wind region with a high spatial resolution of 5 mas (11 AU) and high spectral resolution.
Methods: The observations were carried out with three 8.2 m Unit Telescopes in the K-band. The raw data are spectrally dispersed interferograms obtained with spectral resolutions of 1500 (MR-K mode) and 12 000 (HR-K mode). The MR-K observations were performed in the wavelength range around both the He I 2.059 μm and the Brγ 2.166 μm emission lines, the HR-K observations only in the Brγ line region.
Results: The spectrally dispersed AMBER interferograms allow the investigation of the wavelength dependence of the visibility, differential phase, and closure phase of η Car. In the K-band continuum, a diameter of 4.0±0.2 mas (Gaussian FWHM, fit range 28-89 m baseline length) was measured for η Car's optically thick wind region. If we fit Hillier et al. (2001, ApJ, 553, 837) model visibilities to the observed AMBER visibilities, we obtain 50% encircled-energy diameters of 4.2, 6.5 and 9.6 mas in the 2.17 μm continuum, the He I, and the Brγ emission lines, respectively. In the continuum near the Brγ line, an elongation along a position angle of 120°±15° was found, consistent with previous VINCI/VLTI measurements by van Boekel et al. (2003, A&A, 410, L37). We compare the measured visibilities with predictions of the radiative transfer model of Hillier et al. (2001), finding good agreement. Furthermore, we discuss the detectability of the hypothetical hot binary companion. For the interpretation of the non-zero differential and closure phases measured within the Brγ line, we present a simple geometric model of an inclined, latitude-dependent wind zone. Our observations support theoretical models of anisotropic winds from fast-rotating, luminous hot stars with enhanced high-velocity mass loss near the polar regions.

Based on observations collected at the European Southern Observatory, Paranal, Chile, within the AMBER guaranteed time programme 074.A-9025 and the VLTI science demonstration programme 074.A-9024. Title: Interferometric data reduction with AMBER/VLTI. Principle, estimators, and illustration Authors: Tatulli, E.; Millour, F.; Chelli, A.; Duvert, G.; Acke, B.; Hernandez Utrera, O.; Hofmann, K. -H.; Kraus, S.; Malbet, F.; Mège, P.; Petrov, R. G.; Vannier, M.; Zins, G.; Antonelli, P.; Beckmann, U.; Bresson, Y.; Dugué, M.; Gennari, S.; Glück, L.; Kern, P.; Lagarde, S.; Le Coarer, E.; Lisi, F.; Perraut, K.; Puget, P.; Rantakyrö, F.; Robbe-Dubois, S.; Roussel, A.; Weigelt, G.; Accardo, M.; Agabi, K.; Altariba, E.; Arezki, B.; Aristidi, E.; Baffa, C.; Behrend, J.; Blöcker, T.; Bonhomme, S.; Busoni, S.; Cassaing, F.; Clausse, J. -M.; Colin, J.; Connot, C.; Delboulbé, A.; Domiciano de Souza, A.; Driebe, T.; Feautrier, P.; Ferruzzi, D.; Forveille, T.; Fossat, E.; Foy, R.; Fraix-Burnet, D.; Gallardo, A.; Giani, E.; Gil, C.; Glentzlin, A.; Heiden, M.; Heininger, M.; Kamm, D.; Kiekebusch, M.; Le Contel, D.; Le Contel, J. -M.; Lesourd, T.; Lopez, B.; Lopez, M.; Magnard, Y.; Marconi, A.; Mars, G.; Martinot-Lagarde, G.; Mathias, P.; Monin, J. -L.; Mouillet, D.; Mourard, D.; Nussbaum, E.; Ohnaka, K.; Pacheco, J.; Perrier, C.; Rabbia, Y.; Rebattu, S.; Reynaud, F.; Richichi, A.; Robini, A.; Sacchettini, M.; Schertl, D.; Schöller, M.; Solscheid, W.; Spang, A.; Stee, P.; Stefanini, P.; Tallon, M.; Tallon-Bosc, I.; Tasso, D.; Testi, L.; Vakili, F.; von der Lühe, O.; Valtier, J. -C.; Ventura, N. Bibcode: 2007A&A...464...29T Altcode: 2006astro.ph..3046T Aims:In this paper, we present an innovative data reduction method for single-mode interferometry. It has been specifically developed for the AMBER instrument, the three-beam combiner of the Very Large Telescope Interferometer, but it can be derived for any single-mode interferometer.
Methods: The algorithm is based on a direct modelling of the fringes in the detector plane. As such, it requires a preliminary calibration of the instrument in order to obtain the calibration matrix that builds the linear relationship between the interferogram and the interferometric observable, which is the complex visibility. Once the calibration procedure has been performed, the signal processing appears to be a classical least-square determination of a linear inverse problem. From the estimated complex visibility, we derive the squared visibility, the closure phase, and the spectral differential phase.
Results: The data reduction procedures have been gathered into the so-called amdlib software, now available for the community, and are presented in this paper. Furthermore, each step in this original algorithm is illustrated and discussed from various on-sky observations conducted with the VLTI, with a focus on the control of the data quality and the effective execution of the data reduction procedures. We point out the present limited performances of the instrument due to VLTI instrumental vibrations which are difficult to calibrate.

Based on observations collected

at the European Southern Observatory, Paranal, Chile. Title: Direct constraint on the distance of γ2 Velorum from AMBER/VLTI observations Authors: Millour, F.; Petrov, R. G.; Chesneau, O.; Bonneau, D.; Dessart, L.; Bechet, C.; Tallon-Bosc, I.; Tallon, M.; Thiébaut, E.; Vakili, F.; Malbet, F.; Mourard, D.; Antonelli, P.; Beckmann, U.; Bresson, Y.; Chelli, A.; Dugué, M.; Duvert, G.; Gennari, S.; Glück, L.; Kern, P.; Lagarde, S.; Le Coarer, E.; Lisi, F.; Perraut, K.; Puget, P.; Rantakyrö, F.; Robbe-Dubois, S.; Roussel, A.; Tatulli, E.; Weigelt, G.; Zins, G.; Accardo, M.; Acke, B.; Agabi, K.; Altariba, E.; Arezki, B.; Aristidi, E.; Baffa, C.; Behrend, J.; Blöcker, T.; Bonhomme, S.; Busoni, S.; Cassaing, F.; Clausse, J. -M.; Colin, J.; Connot, C.; Delboulbé, A.; Domiciano de Souza, A.; Driebe, T.; Feautrier, P.; Ferruzzi, D.; Forveille, T.; Fossat, E.; Foy, R.; Fraix-Burnet, D.; Gallardo, A.; Giani, E.; Gil, C.; Glentzlin, A.; Heiden, M.; Heininger, M.; Hernandez Utrera, O.; Hofmann, K. -H.; Kamm, D.; Kiekebusch, M.; Kraus, S.; Le Contel, D.; Le Contel, J. -M.; Lesourd, T.; Lopez, B.; Lopez, M.; Magnard, Y.; Marconi, A.; Mars, G.; Martinot-Lagarde, G.; Mathias, P.; Mège, P.; Monin, J. -L.; Mouillet, D.; Nussbaum, E.; Ohnaka, K.; Pacheco, J.; Perrier, C.; Rabbia, Y.; Rebattu, S.; Reynaud, F.; Richichi, A.; Robini, A.; Sacchettini, M.; Schertl, D.; Schöller, M.; Solscheid, W.; Spang, A.; Stee, P.; Stefanini, P.; Tasso, D.; Testi, L.; von der Lühe, O.; Valtier, J. -C.; Vannier, M.; Ventura, N. Bibcode: 2007A&A...464..107M Altcode: 2006astro.ph.10936M Context: Interferometry can provide spatially resolved observations of massive star binary systems and their colliding winds, which thus far have been studied mostly with spatially unresolved observations.
Aims: We present the first AMBER/VLTI observations, taken at orbital phase 0.32, of the Wolf-Rayet and O (WR+O) star binary system γ2 Velorum and use the interferometric observables to constrain its properties.
Methods: The AMBER/VLTI instrument was used with the telescopes UT2, UT3, and UT4 on baselines ranging from 46 m to 85 m. It delivered spectrally dispersed visibilities, as well as differential and closure phases, with a resolution R=1500 in the spectral band 1.95-2.17 μm. We interpret these data in the context of a binary system with unresolved components, neglecting in a first approximation the wind-wind collision zone flux contribution.
Results: Using WR- and O-star synthetic spectra, we show that the AMBER/VLTI observables result primarily from the contribution of the individual components of the WR+O binary system. We discuss several interpretations of the residuals, and speculate on the detection of an additional continuum component, originating from the free-free emission associated with the wind-wind collision zone (WWCZ), and contributing at most to the observed K-band flux at the 5% level. Based on the accurate spectroscopic orbit and the Hipparcos distance, the expected absolute separation and position angle at the time of observations were 5.1±0.9 mas and 66±15°, respectively. However, using theoretical estimates for the spatial extent of both continuum and line emission from each component, we infer a separation of 3.62+0.11-0.30 mas and a position angle of 73+9-11°, compatible with the expected one. Our analysis thus implies that the binary system lies at a distance of 368+38-13 pc, in agreement with recent spectrophotometric estimates, but significantly larger than the Hipparcos value of 258+41-31 pc.

Based on observations collected at the European Southern Observatory, Paranal, Chile, within the guaranteed time programme 074.A-9025(A). Title: Optical configuration and analysis of the AMBER/VLTI instrument Authors: Robbe-Dubois, S.; Lagarde, S.; Petrov, R. G.; Lisi, F.; Beckmann, U.; Antonelli, P.; Bresson, Y.; Martinot-Lagarde, G.; Roussel, A.; Salinari, P.; Vannier, M.; Chelli, A.; Dugué, M.; Duvert, G.; Gennari, S.; Glück, L.; Kern, P.; Le Coarer, E.; Malbet, F.; Millour, F.; Perraut, K.; Puget, P.; Rantakyrö, F.; Tatulli, E.; Weigelt, G.; Zins, G.; Accardo, M.; Acke, B.; Agabi, K.; Altariba, E.; Arezki, B.; Aristidi, E.; Baffa, C.; Behrend, J.; Blöcker, T.; Bonhomme, S.; Busoni, S.; Cassaing, F.; Clausse, J. -M.; Colin, J.; Connot, C.; Delage, L.; Delboulbé, A.; Domiciano de Souza, A.; Driebe, T.; Feautrier, P.; Ferruzzi, D.; Forveille, T.; Fossat, E.; Foy, R.; Fraix-Burnet, D.; Gallardo, A.; Giani, E.; Gil, C.; Glentzlin, A.; Heiden, M.; Heininger, M.; Hernandez Utrera, O.; Hofmann, K. -H.; Kamm, D.; Kiekebusch, M.; Kraus, S.; Le Contel, D.; Le Contel, J. -M.; Lesourd, T.; Lopez, B.; Lopez, M.; Magnard, Y.; Marconi, A.; Mars, G.; Mathias, P.; Mège, P.; Monin, J. -L.; Mouillet, D.; Mourard, D.; Nussbaum, E.; Ohnaka, K.; Pacheco, J.; Perrier, C.; Rabbia, Y.; Rebattu, S.; Reynaud, F.; Richichi, A.; Robini, A.; Sacchettini, M.; Schertl, D.; Schöller, M.; Solscheid, W.; Spang, A.; Stee, P.; Stefanini, P.; Tallon, M.; Tallon-Bosc, I.; Tasso, D.; Testi, L.; Vakili, F.; von der Lühe, O.; Valtier, J. -C.; Ventura, N. Bibcode: 2007A&A...464...13R Altcode: 2008arXiv0807.3717R Aims:This paper describes the design goals and engineering efforts that led to the realization of AMBER (Astronomical Multi BEam combineR) and to the achievement of its present performance.
Methods: On the basis of the general instrumental concept, AMBER was decomposed into modules whose functions and detailed characteristics are given. Emphasis is put on the spatial filtering system, a key element of the instrument. We established a budget for transmission and contrast degradation through the different modules, and made the detailed optical design. The latter confirmed the overall performance of the instrument and defined the exact implementation of the AMBER optics.
Results: The performance was assessed with laboratory measurements and commissionings at the VLTI, in terms of spectral coverage and resolution, instrumental contrast higher than 0.80, minimum magnitude of 11 in K, absolute visibility accuracy of 1%, and differential phase stability of 10-3 rad over one minute. Title: History, Present Status & Future of Site Testing at Dôme C Authors: Vernin, J.; Agabi, A.; Aristidi, E.; Azouit, M.; Chadid, M.; Fossat, E.; Sadibekova, T.; Trinquet, H.; Ziad, A. Bibcode: 2007EAS....25...23V Altcode: Hereafter we give a brief history of our contribution to astronomical site testing in Antarctica, at least for the high angular resolution in the visible range. The decision to undertake the first site testing at South Pole began one year after a congress organized by French Académie des Sciences, in year 1992. Indeed, in 1993 a meeting took place in Chicago with the participation of Peter Gillingham, Al Harper and Jean Vernin where each one took the respective responsibility of 1) giving a PhD student, 2) the South Pole infrastructure and 3) the relevant instruments. During winter 1995, thanks to a mast equipped with micro-thermal sensors, we demonstrated (Marks et al., 1996, A&AS, 118, 1) that the first 30 m of the surface layer was disrupted by strong optical turbulence. Then, the year after, 15 balloons equipped with micro-thermal probes were successfully launched from South Pole. Marks et al. (1999, A&AS, 134, 161) shown that most of the optical turbulence at South Pole was concentrated within a layer 200 m thick above the ice level. From this study, it becomes clear that the noticeable katabatic wind present at South Pole was generating this huge surface layer and that is why we oriented our astronomical site characterization toward Dôme C. Our first summer seeing estimations began in 2000, which demonstrated (Aristidi et al., 2003, A&AS, 406, L19 & Aristidi et al., 2005, A&A, 444, 651) that, as expected, the surface wind was much less than at South Pole, and, as a matter of fact, the seeing was much better, and was even exceptional during the four hours of the afternoon where a seeing of less than 0.5 arcsec was measured. In 2005, the Concordia base was first open during the polar night, and one of us, A. Agabi was able to launch 41 balloons equipped with micro-thermal sensors. A differential image motion monitor (DIMM) was also setup with success. At mid winter, Agabi et al. (2006, PASP, 118, 344) showed that most of the optical turbulence came from the first 30 m surface layer and very little from the rest of the atmosphere (1.3 arcsec above 8.5 m and 0.37 arcsec above 30 m). Title: Choosing Dome C, Antarctic Plateau as Future Astronomical Observatory Authors: Sadibekova, T.; Fossat, E.; Vernin, J.; Agabi, A.; Aristidi, E.; Azouit, M.; Chadid, M.; Trinquet, H.; Genthon, C.; Krinner, G.; Sarazin, M. Bibcode: 2007EAS....25...69S Altcode: In this paper we present year-round climatological analysis made from radio-sounding measurements and ECMWF Data. And we end up with a generalized conclusion (scientific aspect) from statistical results of site-testing at Concordia concerning the feasibility of the future astronomical exploitation of Dome C. Title: Dome C: An exceptional site for solar observations . Authors: Arnaud, J.; Faurobert, M.; Fossat, E. Bibcode: 2007MmSAI..78..105A Altcode: Dome C, on the Antarctica plateau, may be the best site on Earth for astronomy, thanks to outstanding image quality and very pure and cold atmosphere. This is of particular interest for solar physics, namely for very high-resolution studies of the solar surface and for magnetometry of the innermost solar corona. Here we review Dome C unique atmospheric properties and present two projects aimed at quantitatively qualify this site for solar observations. Title: GIVRE: A Protection Against Frost Deposit on Polar Instruments Authors: Durand, G.; Cadelis, L.; Minier, V.; Veyssière, C.; Walter, C.; Pierre, A.; Agabi, A.; Fossat, E.; Jeanneaux, F. Bibcode: 2007EAS....25...77D Altcode: The CEA, in coordination with IPEV and LUAN, will prepare an experiment to study frost formation on surfaces in radiative cooling in the winter. This experiment has been shipped to be installed at Concordia before the 2007 winter period. It will be controlled from Concordia winterover personal, through PC server that will locally archive data from WEBcams and several local heat regulators. This experiment will be used to give recipes on the way to compensate with heaters the radiative cooling from the sky and maintain instrument surfaces at temperature just above icing conditions. The individual regulators proposed in this experiment will be usable as standalone ice protection systems for existing and future telescopes. Title: Stella Antarctica An I.P.Y. Programme Towards an International Astronomical Observatory at Dome C, Antarctica Authors: Fossat, E. Bibcode: 2007EAS....25...19F Altcode: This paper describes STELLA ANTARCTICA, one of the two astronomical projects sponsored by the International Polar Year. Title: The DynaMICS perspective Authors: Turck-Chièze, S.; Schmutz, W.; Thuillier, G.; Jefferies, S.; Pallé; Dewitt, S.; Ballot, J.; Berthomieu, G.; Bonanno, A.; Brun, A. S.; Christensen-Dalsgaard, J.; Corbard, T.; Couvidat, S.; Darwich, A. M.; Dintrans, B.; Domingo, V.; Finsterle, W.; Fossat, E.; Garcia, R. A.; Gelly, B.; Gough, D.; Guzik, J.; Jiménez, A. J.; Jiménez-Reyes, S.; Kosovichev, A.; Lambert, P.; Lefebvre, S.; Lopes, I.; Martic, M.; Mathis, S.; Mathur, S.; Nghiem, P. A. P.; Piau, L.; Provost, J.; Rieutord, M.; Robillot, J. M.; Rogers, T.; Roudier, T.; Roxburgh, I.; Rozelot, J. P.; Straka, C.; Talon, S.; Théado, S.; Thompson, M.; Vauclair, S.; Zahn, J. P. Bibcode: 2006ESASP.624E..24T Altcode: 2006soho...18E..24T No abstract at ADS Title: 6 years of site testing at Concordia Authors: Fossat, E. G. Bibcode: 2006IAUSS...7E...3F Altcode: The Concordiastro site testing programme has been started in November, 2000. Six summer seasons have already been extensively tested, and the second winter is now under way. The statistical astronomical properties of the local sky are now well known. They will be reviewed, as well as those additional ionformations that still require more studies. Title: Atmospheric scintillation at Dome C, Antarctica: implications for photometry and astrometry Authors: Kenyon, S.; Lawrence, J.; Ashley, M. C. B.; Storey, J. W. V.; Tokovinin, A.; Fossat, E. Bibcode: 2006IAUSS...7E..30K Altcode: Night-time turbulence profiles of the atmosphere above Dome C, Antarctica, were measured during 2004, using a MASS instrument. We compare this data with turbulence profiles above Cerro Tololo and Cerro Pachon, also measured with a MASS, and find, with the exception of the owest layer, that Dome C has significantly less turbulence. In addition, the integrated at turbulence 16 km above Dome C is always less than the median values at the two Chilean sites. Using average wind speed profiles, we assess the photometric noise produced by scintillation, and the atmospheric contribution to the error budget in narrow angle differential astrometry. In comparison with the two mid-latitude sites in Chile, Dome C offers a potential gain of about 3.6 in both photometric precision (for long integrations) and narrow-angle astrometry precision. Although the data from Dome C cover a fairly limited time frame, they lend strong support to expectations that Dome C will offer significant advantages for photometric and astrometric studies. Title: Site Testing At Dome C: History, Present Status & Futur Authors: Vernin, J.; Agabi, A.; Aristidi, E.; Azouit, M.; Chadid-Vernin, M.; Fossat, E.; Sadibekova, T.; Ziad, A. Bibcode: 2006IAUSS...7E..17V Altcode: Here we present why we decided to undertake a site characterization at Dome C, Antarctica following a first step made at South Pole. It was clear that poor seeing measured at South Pole was mainly due to ground catabatic wind interacting with strong vertical temperature (refractive index) gradient. Thus, we though to move to Dome C where no catabatic wind is expected. We will recall the history of this long adventure. Then we will present the more recent results which concern daytime observations as well as nighttime observations, as measured by DIMM, balloons, GSM and SSS. From this database and the very special vertical distribution fo the optical turbulence at Dome C, we will present some strong implications for High Angular Resolution astronomy at Dome C. Title: Scientific Objectives of the Novel Formation Flying Mission Aspiics Authors: Turck-Chièze, S.; Schmutz, W.; Thuillier, G.; Jefferies, S.; Pallé; Dewitt, S.; Ballot, J.; Berthomieu, G.; Bonanno, A.; Brun, A. S.; Christensen-Dalsgaard, J.; Corbard, T.; Couvidat, S.; Darwich, A. M.; Dintrans, B.; Domingo, V.; Finsterle, W.; Fossat, E.; Garcia, R. A.; Gelly, B.; Gough, D.; Guzik, J.; Jiménez, A. J.; Jiménez-Reyes, S.; Kosovichev, A.; Lambert, P.; Lefebvre, S.; Lopes, I.; Martic, M.; Mathis, S.; Mathur, S.; Nghiem, P. A. P.; Piau, L.; Provost, J.; Rieutord, M.; Robillot, J. M.; Rogers, T.; Roudier, T.; Roxburgh, I.; Rozelot, J. P.; Straka, C.; Talon, S.; Théado, S.; Thompson, M.; Vauclair, S.; Zahn, J. P. Bibcode: 2006ESASP.617E.164L Altcode: 2006soho...17E.164L No abstract at ADS Title: The EUV Variability Experiment (EVE) on the Solar Dynamics Observatory (SDO): Science Plan and Instrument Overview Authors: Turck-Chièze, S.; Schmutz, W.; Thuillier, G.; Jefferies, S.; Pallé; Dewitt, S.; Ballot, J.; Berthomieu, G.; Bonanno, A.; Brun, A. S.; Christensen-Dalsgaard, J.; Corbard, T.; Couvidat, S.; Darwich, A. M.; Dintrans, B.; Domingo, V.; Finsterle, W.; Fossat, E.; Garcia, R. A.; Gelly, B.; Gough, D.; Guzik, J.; Jiménez, A. J.; Jiménez-Reyes, S.; Kosovichev, A.; Lambert, P.; Lefebvre, S.; Lopes, I.; Martic, M.; Mathis, S.; Mathur, S.; Nghiem, P. A. P.; Piau, L.; Provost, J.; Rieutord, M.; Robillot, J. M.; Rogers, T.; Roudier, T.; Roxburgh, I.; Rozelot, J. P.; Straka, C.; Talon, S.; Théado, S.; Thompson, M.; Vauclair, S.; Zahn, J. P. Bibcode: 2006ESASP.617E.165W Altcode: 2006soho...17E.165W No abstract at ADS Title: The Dynamics Project Authors: Turck-Chièze, S.; Schmutz, W.; Thuillier, G.; Jefferies, S.; Pallé; Dewitt, S.; Ballot, J.; Berthomieu, G.; Bonanno, A.; Brun, A. S.; Christensen-Dalsgaard, J.; Corbard, T.; Couvidat, S.; Darwich, A. M.; Dintrans, B.; Domingo, V.; Finsterle, W.; Fossat, E.; Garcia, R. A.; Gelly, B.; Gough, D.; Guzik, J.; Jiménez, A. J.; Jiménez-Reyes, S.; Kosovichev, A.; Lambert, P.; Lefebvre, S.; Lopes, I.; Martic, M.; Mathis, S.; Mathur, S.; Nghiem, P. A. P.; Piau, L.; Provost, J.; Rieutord, M.; Robillot, J. M.; Rogers, T.; Roudier, T.; Roxburgh, I.; Rozelot, J. P.; Straka, C.; Talon, S.; Théado, S.; Thompson, M.; Vauclair, S.; Zahn, J. P. Bibcode: 2006ESASP.617E.162T Altcode: 2006soho...17E.162T No abstract at ADS Title: Atmospheric Scintillation at Dome C, Antarctica: Implications for Photometryand Astrometry Authors: Kenyon, S. L.; Lawrence, J. S.; Ashley, M. C. B.; Storey, J. W. V.; Tokovinin, A.; Fossat, E. Bibcode: 2006PASP..118..924K Altcode: 2006astro.ph..4538K We present low-resolution turbulence profiles of the atmosphere above Dome C, Antarctica, measured with the MASS instrument during 25 nights in 2004 March-May. Except for the lowest layer, Dome C has significantly less turbulence than Cerro Tololo and Cerro Pachón. In particular, the integrated turbulence at 16 km is always less than the median values at the two Chilean sites. From these profiles we evaluate the photometric noise produced by scintillation, and the atmospheric contribution to the error budget in narrow-angle differential astrometry. In comparison with the two midlatitude sites in Chile, Dome C offers a potential gain of about 3.6 in both photometric precision (for long integrations) and narrow-angle astrometry precision. These gain estimates are preliminary, being computed with average wind-speed profiles, but the validity of our approach is confirmed by independent data. Although the data from Dome C cover a fairly limited time frame, they lend strong support to expectations that Dome C will offer significant advantages for photometric and astrometric studies. Title: Solar FLAG hare and hounds: on the extraction of rotational p-mode splittings from seismic, Sun-as-a-star data Authors: Chaplin, W. J.; Appourchaux, T.; Baudin, F.; Boumier, P.; Elsworth, Y.; Fletcher, S. T.; Fossat, E.; García, R. A.; Isaak, G. R.; Jiménez, A.; Jiménez-Reyes, S. J.; Lazrek, M.; Leibacher, J. W.; Lochard, J.; New, R.; Pallé, P.; Régulo, C.; Salabert, D.; Seghouani, N.; Toutain, T.; Wachter, R. Bibcode: 2006MNRAS.369..985C Altcode: 2006MNRAS.tmp..515C; 2006astro.ph..6748C We report on results from the first solar Fitting at Low-Angular degree Group (solar FLAG) hare-and-hounds exercise. The group is concerned with the development of methods for extracting the parameters of low-l solar p-mode data (`peak bagging'), collected by Sun-as-a-star observations. Accurate and precise estimation of the fundamental parameters of the p modes is a vital pre-requisite of all subsequent studies. Nine members of the FLAG (the `hounds') fitted an artificial 3456-d data set. The data set was made by the `hare' (WJC) to simulate full-disc Doppler velocity observations of the Sun. The rotational frequency splittings of the l = 1, 2 and 3 modes were the first parameter estimates chosen for scrutiny. Significant differences were uncovered at l = 2 and 3 between the fitted splittings of the hounds. Evidence is presented that suggests this unwanted bias had its origins in several effects. The most important came from the different way in which the hounds modelled the visibility ratio of the different rotationally split components. Our results suggest that accurate modelling of the ratios is vital to avoid the introduction of significant bias in the estimated splittings. This is of importance not only for studies of the Sun, but also of the solar analogues that will be targets for asteroseismic campaigns.

Solar FLAG URL: http://bison.ph.bham.ac.uk/~wjc/Research/FLAG.html

E-mail: wjc@bison.ph.bham.ac.uk ‡

George Isaak passed away in 2005 June 5, prior to the completion of this work. He is greatly missed by us all. Title: Jovian seismology: preliminary results of the SYMPA instrument Authors: Gaulme, P.; Schmider, F. X.; Gay, J.; Jacob, C.; Jeanneaux, F.; Alvarez, M.; Reyes, M.; Valtier, J. C.; Fossat, E.; Palle, P. L.; Belmonte, J. C.; Gelly, B. Bibcode: 2006sf2a.conf..403G Altcode: Jupiter's internal structure is poorly known (Guillot et al. 2004). Seismology is a powerful tool to investigate the internal structure of planets and stars, by analyzing how acoustic waves propagate. Mosser (1997) and Gudkova & Zarkhov (1999) showed that the detection and the identification of non-radial modes up to degree ℓ=25 can constrain strongly the internal structure. SYMPA is a ground-based network project dedicated to the Jovian oscillations (Schmider et al. 2002). The instrument is composed of a Mach-Zehnder interferometer producing four interferograms of the planetary spectrum. The combination of the four images in phase quadrature allows the reconstruction of the incident light phase, which is related to the Doppler shift generated by the oscillations. Two SYMPA instruments were built at the Nice university and were used simultaneously during two observation campaigns, in 2004 and 2005, at the San Pedro Martir observatory (Mexico) and the Teide observatory (Las Canarias). We will present for the first time the data processing and the preliminary results of the experiment. Title: First Whole Atmosphere Nighttime Seeing Measurements at Dome C, Antarctica Authors: Agabi, A.; Aristidi, E.; Azouit, M.; Fossat, E.; Martin, F.; Sadibekova, T.; Vernin, J.; Ziad, A. Bibcode: 2006PASP..118..344A Altcode: 2005astro.ph.10418A We report site-testing results obtained in the nighttime during the polar autumn and winter at Dome C. These results were collected during the first Concordia winterover by A. Agabi. They are based on seeing and isoplanatic angle monitoring, as well as in situ balloon measurements of the refractive index structure constant profiles C2n(h). Atmosphere is divided into two regions: (1) a 36 m high surface layer responsible for 87% of the turbulence, and (2) a very stable free atmosphere above, with a median seeing of 0.36" +/- 0.19" at an elevation of h=30 m. The median seeing measured with a differential image motion monitor placed on top of an 8.5 m high tower is 1.3" +/- 0.8". Title: GOLF-NG spectrometer, a space prototype for studying the dynamics of the deep solar interior Authors: Turck-Chièze, Sylvaine; Carton, Pierre-Henri; Ballot, Jérome; Barrière, Jean-Christophe; Daniel-Thomas, Philippe; Delbart, Alain; Desforges, Daniel; Garcia, Rafaël A.; Granelli, Rémi; Mathur, Savita; Nunio, François; Piret, Yves; Pallé, Pere L.; Jiménez, Antonio J.; Jiménez-Reyes, Sebastian J.; Robillot, Jean Maurice; Fossat, Eric; Eff-Darwich, Antonio. M.; Gelly, Bernard Bibcode: 2006AdSpR..38.1812T Altcode: 2005astro.ph.10753T The GOLF-NG (Global Oscillations at Low Frequency New Generation) instrument is devoted to the search for solar gravity and acoustic modes, and also chromospheric modes from space. This instrument which is a successor to GOLF/SOHO will contribute to improve our knowledge of the dynamics of the solar radiative zone. It is a 15 points resonant scattering spectrometer, working on the D1 sodium line. A ground-based prototype is under construction to validate the difficult issues. It will be installed at the Teide Observatory, on Tenerife in 2006 to analyse the separation of the effects of the magnetic turbulence of the line from the solar oscillations. We are prepared to put a space version of this instrument including a capability of identification of the modes, in orbit during the next decade. This instrument should be included in the ILWS program as it offers a key to the improvement of our knowledge of the solar core in combination with observations from SDO and PICARD. We hope to determine the core rotation and magnetic field, through precise measurements of oscillation mode frequency splittings. Understanding the magnetic field of the radiative zone is important for progress in the study of solar activity sources, an important player for the long-term Sun-Earth relationship. Title: Site testing in winter at Dome C Authors: Aristidi, E.; Agabi, A.; Fossat, E.; Azouit, M.; Vernin, J.; Sadibekova, T.; Travouillon, T.; Ziad, A.; Martin, F. Bibcode: 2005sf2a.conf...45A Altcode: We present site testing results obtained in night-time during the polar winter at Dome C. These results were collected during the first Concordia winterover by A. Agabi. They are based upon seeing and isoplanatic angle monitoring, as well as in-situ balloon measurements of the refractive index structure constant profiles Cn2(h). Atmosphere is divided into two regions: (i) a 36 m high surface layer responsible of 87% of the turbulence and (ii) a very stable free atmosphere above with a median seeing of 0.36±0.19 arcsec at an elevation of h=30m. The median seeing measured with a DIMM placed on top of a 8.5 m high tower is 1.3±0.8 arcsec. Title: Working group report on Asteroseismology and stellar activity from Dome C Authors: Bouchy, F.; Mosser, B.; Catala, C.; Appourchaux, T.; Bouvier, J.; Chadid, M.; Donati, J. F.; Fossat, E.; Schmider, F. X.; Thevenin, F.; Vauclair, G. Bibcode: 2005sf2a.conf..329B Altcode: This paper presents the conclusions of the working group for stellar physics observations at the Dome-C station in Antarctica. It summarizes the advantages of Dome-C for asteroseismology and stellar activity, identifies strategies and possible instrumental projects to be conducted there, and concludes with recommendations for the development of stellar observations. The conclusions are based on the fact that continuous observations over several weeks or months without breaks due to the diurnal cycle are fundamental for programs of stellar physics and especially for asteroseismology and stellar activity. Therefore, Dome-C appears to be a unique ground-based site offering ideal conditions for continuous observations. Title: Site testing in summer at Dome C, Antarctica Authors: Aristidi, E.; Agabi, A.; Fossat, E.; Azouit, M.; Martin, F.; Sadibekova, T.; Travouillon, T.; Vernin, J.; Ziad, A. Bibcode: 2005A&A...444..651A Altcode: 2005astro.ph..7475A We present summer site testing results based on DIMM data obtained at Dome C, Antarctica. These data were collected on the bright star Canopus during two 3-months summer campaigns in 2003-2004 and 2004-2005. We performed continuous monitoring of the seeing and the isoplanatic angle in the visible. We found a median seeing of 0.54'' and a median isoplanatic angle of 6.8''. The seeing appears to have a deep minimum around 0.4'' almost every day in late afternoon. Title: The Concordia Station on the Antarctic Plateau: The Best Site on Earth for the 21st Century Astronomers Authors: Fossat, Eric Bibcode: 2005JApA...26..349F Altcode: On the Antarctic plateau, a joint project of French and Italian polar programmes is nearing completion: the Concordia station will be open for winter-over operation in 2005. The high altitude and high latitude of this site, the exceptionally cold, clear and stable atmosphere, its incredible astronomical seeing, the almost indefinitely flat snow surface and the not-so- difficult access make this site the most promising on Earth for future ground-based astronomical projects in various fields, including long term photometry, infrared high sensitivity imaging and high angular resolution and high contrast imaging. Title: An analysis of temperatures and wind speeds above Dome C, Antarctica Authors: Aristidi, E.; Agabi, K.; Azouit, M.; Fossat, E.; Vernin, J.; Travouillon, T.; Lawrence, J. S.; Meyer, C.; Storey, J. W. V.; Halter, B.; Roth, W. L.; Walden, V. Bibcode: 2005A&A...430..739A Altcode: A good astronomical site must fulfill several criteria including low atmospheric turbulence and low wind speeds. It is therefore important to have a detailed knowledge of the temperature and wind conditions of a location considered for future astronomical research. Antarctica has unique atmospheric conditions that have already been exploited at the South Pole station. Dome C, a site located on a local maximum of the Antarctic plateau, is likely to have even better conditions. In this paper we present the analysis of two decades of wind speed measurements taken at Dome C by an automated weather station (AWS). We also present temperature and wind speed profiles taken over four Antarctic summers using balloon-borne weather sondes. We will show that as well as having one of the lowest average wind speed ever recorded at an existing or potential observatory, Dome C also has an extremely stable upper atmosphere and a very low inversion layer. Title: Asteroseismology and Stellar Pulsation feasibility at Dome C Authors: Chadid, M.; Vernin, J.; Fossat, E. Bibcode: 2005EAS....14..281C Altcode: Four site testing campaigns have already been conducted at Dome C during the local summers. A very reasonable extrapolation of the knowledge acquired on the atmospheric properties shows that broad band photometry could be exploited there for developing asteroseismology of many pulsating stars, including the solar-type ones, despite their very small oscillation amplitudes. This paper focuses more specifically on the usual limiting factor in photometry which is the scintillation. Title: JISCO: Jovian Interferometric Seismometer at Concordia Observatory Authors: Schmider, F. X.; Jacob, C.; Fossat, E.; Abe, L.; Gay, J.; Valtier, J. -C.; Guillot, T.; Provost, J.; Mosser, B.; Gaulme, P. Bibcode: 2005EAS....14..285S Altcode: Seismology is the only way to investigate the internal structure of the giant planets, with a lot of scientific implications such as high pressure physics and huge constraints on the scenario of solar system formation. As compared to other existing possibilities (ground based network, spacecraft), seismology of Jupiter will take a maximum benefit from the peculiarities of the Concordia station as an astronomical observatory. Indeed, the continuous temporal coverage for all the winter season, and the quality of the atmospheric seeing, are crucial parameters for this program. The jovian seismometer SYMPA, already used for network observations, is perfectly suitable for Dome C conditions. With the already existing small telescopes deployed in the frame of site testing program, seismology of Jupiter will constitute a excellent intermediate project with high scientific return, before the installation of large telescopes. In a second step, such an instrument could be a first light instrument for a 1.5 m class automatic telescope, which is to be developed as an individual stone for a large interferometer. With this diameter, the same scientific program on Saturn could also be achieved. Title: Asteroseismology Authors: Fossat, E. Bibcode: 2005EAS....14..121F Altcode: Regarding its seeing properties or its photometric quality as well, the Dome C Concordia site is presented as being an intermediate solution between space and a good mountain observatory. This statement still needs somewhat further night time confirmation. If really true, as is more and more expected after the preliminary site testing campaigns (Aristidi et al. 2004; Storey et al. 2004), this opens extremely promising prospects for asteroseismology of solar-type stars, and also of any kind of star for which a continuous observation much longer than 12 hours is an important requirement. Title: Site testing study based on weather balloons measurements Authors: Aristidi, E.; Agabi, A.; Azouit, M.; Fossat, E.; Vernin, J.; Sadibekova, T.; Travouillon, T.; Lawrence, J. S.; Halter, B.; Roth, W. L.; Walden, V. P. Bibcode: 2005EAS....14..227A Altcode: 2018arXiv181200028A We present wind and temperature profiles at Dome C measured during the polar summer by balloon born sonds. Data from 197 flights have been processed for 4 campaigns between 2000 and 2004. We show the exceptionnal wind conditions at Dome C: averaged ground wind speed is 3.6 m s-1. We noticed in mid-november the presence of high altitude strong winds (40 m s-1) probably due to the polar vortex which disappear in summer. These winds seem to have no effect on seeing measurements made with a DIMM at the same period. Temperature profiles exhibit a minimum at height 5500 m (over the snow surface) that defines the tropopause. Surface layer temperature profile has negative gradient in the first 50 m above ground in the afternoon and a strong inversion layer (5°C over 50 m) around midnight. Wind profiles are compared with other astronomical sites, and with a meteorological model from Meteo France. Title: Setting the Scene Authors: Fossat, E. Bibcode: 2005EAS....14....1F Altcode: The Concordia station on the Antarctica plateau will open very soon its winter-over activities. Astronomy is among the top priorities, because of the unique qualities that are being demonstrated step by step by the site testing programmes Concordiastro and Aastino. Title: Daytime site testing at Dome C: Results of 2003 2004 campaign Authors: Aristidi, E.; Agabi, A.; Fossat, E.; Travouillon, T.; Azouit, M.; Vernin, J.; Ziad, A.; Martin, F.; Robuchon, G. Bibcode: 2005EAS....14...13A Altcode: We present results of daytime site testing at Dome C in summer 2003 2004. Daytime seeing has been monitored during 2 1/2 months using a DIMM on the bright star Canopus, giving median value of 0.54 arcsec. An every-day best seeing period has been observed around 5 pm with seeing around 0.3 arcsec. First isoplanatic angle measurements, based on stellar scintillation, were also performed during the month of January 2004, and have given median value of 6.8 arcsec. Title: KEOPS: towards exo-Earths from Dome C of Antarctica Authors: Vakili, F.; Aristidi, E.; Schmider, F. X.; Jankov, S.; Fossat, E.; Abe, L.; Domiciano, A.; Belu, A.; Agabi, A.; Daban, J. -B.; Robbe-Dubois, S.; Petrov, R.; Vernin, J.; Ziad, A.; Lopez, B. Bibcode: 2005EAS....14..211V Altcode: This paper describes a coronagraphic nulling interferometer called KEOPS (Kiloparsec Explorer for Optical Planet Search) to be placed on the Dome C plateau of Antarctica. KEOPS is an interferometric array of 39 1m 2m telescopes spread over kilometric baselines and operated in the thermal IR region. It could search and characterize all potential exoEarths within the 1 kpc diameter region observable from Dome C. We argue that even in the very difficult operation conditions of Antarctica, such a facility can compete at a much lower cost with the non-zero risk space missions, both for for ExPNs search and their spectroscopic characterization plus sub-mas snap-shot imaging of galactic and extra-galactic compact sources. Title: Flag Hare-And Exercise: on the Extraction of Sectoral Mode Splittings from Full-Disc Sun-As Data Authors: Chaplin, W. J.; Appourchaux, T.; Baudin, F.; Boumier, P.; Elsworth, Y.; Fletcher, S. T.; Fossat, E.; García, R. A.; Isaak, G. R.; Jiménez, A.; Jiménez-Reyes, S. J.; Lazrek, M.; Lochard, J.; New, R.; Pallé, P.; Régulo, C.; Salabert, D.; Toutain, T. Bibcode: 2004ESASP.559..356C Altcode: 2004soho...14..356C No abstract at ADS Title: GOLF Low Degree P-Mode Frequencies and Splittings Accurately Corrected for the Solar Magnetic Activity Authors: Lazrek, M.; Fossat, E.; Grec, G.; Renaud, C.; Schmider, F. X. Bibcode: 2004ESASP.559..528L Altcode: 2004soho...14..528L No abstract at ADS Title: The Antarctic planet interferometer Authors: Swain, Mark R.; Walker, Christopher K.; Traub, Wesley A.; Storey, John W.; Coudé du Foresto, Vincent; Fossat, Eric; Vakili, Farrokh; Stark, Anthony A.; Lloyd, James P.; Lawson, Peter R.; Burrows, Adam S.; Ireland, Michael; Millan-Gabet, Rafael; van Belle, Gerard T.; Lane, Benjamin F.; Vasisht, Gautam; Travouillon, Tony Bibcode: 2004SPIE.5491..176S Altcode: The Antarctic Planet Interferometer is a concept for an instrument designed to detect and characterize extrasolar planets by exploiting the unique potential of the best accessible site on earth for thermal infrared interferometry. High-precision interferometric techniques under development for extrasolar planet detection and characterization (differential phase, nulling and astrometry) all benefit substantially from the slow, low-altitude turbulence, low water vapor content, and low temperature found on the Antarctic plateau. At the best of these locations, such as the Concordia base being developed at Dome C, an interferometer with two-meter diameter class apertures has the potential to deliver unique science for a variety of topics, including extrasolar planets, active galactic nuclei, young stellar objects, and protoplanetary disks. Title: Gravity Modes with a Resonant Scattering Spectrophotometer Authors: Turck-Chièze, S.; Garcia, R. A.; Couvidat, S.; Ballot, J.; Jiménez-Reyes, S. J.; Fossat, E.; Gelly, B.; Mathur, S.; Nghiem, P. A. P.; Pallé, P.; Robillot, Jm.; GOLF-Ng Technical Team Bibcode: 2004ESASP.559...85T Altcode: 2004soho...14...85T No abstract at ADS Title: KEOPS: Kiloparsec Explorer for Optical Planet Search, a direct-imaging optical array at Dome C of Antarctica Authors: Vakili, Farrokh; Belu, Adrian; Aristidi, Eric; Fossat, Eric; Maillard, A.; Abe, Lyu; Agabi, Karim; Vernin, Jean; Baptiste Daban, Jean; Hertmanni, Wilfried; Schmider, Francois-Xavier; Assus, Pierre; Coudé du Foresto, Vincent; Swain, Mark R. Bibcode: 2004SPIE.5491.1580V Altcode: Recent site seeing testing campaigns conducted by our team from University of Nice1 show that Dome C represents the best site on Earth for astronomical high angular resolution (HAR) observations at optical and IR wavelengths. The dramatic gain over relevant HAR parameters r0, L0, θ0 and τ0, added to very low temperatures during the polar winter nights (-70°C), the dry atmosphere and the possibility of continuous observations during several nights make Dome C the ideal site for deploying a kilometric optical interferometer before the 2015 horizon. Here we describe the concept of Kiloparsec Explorer for Optical Planet Search (KEOPS) that is studied by our group at LUAN. KEOPS is an interferometric array of 36 off-axis telescopes, each 1.5m in diameter. Its kilometric baselines open sub-mas snap-shot imaging possibilities to detect and characterize extra-solar planetary systems, especially exo-Earths out to 300 parsecs from the visible to the thermal IR. KEOPS can be considered as a DARWIN/TPF challenger but at a much lower cost. Title: About the rotation of the solar radiative interior Authors: García, R. A.; Corbard, T.; Chaplin, W. J.; Couvidat, S.; Eff-Darwich, A.; Jiménez-Reyes, S. J.; Korzennik, S. G.; Ballot, J.; Boumier, P.; Fossat, E.; Henney, C. J.; Howe, R.; Lazrek, M.; Lochard, J.; Pallé, P. L.; Turck-Chièze, S. Bibcode: 2004SoPh..220..269G Altcode: In the modern era of helioseismology we have a wealth of high-quality data available, e.g., more than 6 years of data collected by the various instruments on board the SOHO mission, and an even more extensive ground-based set of observations covering a full solar cycle. Thanks to this effort a detailed picture of the internal rotation of the Sun has been constructed. In this paper we present some of the actions that should be done to improve our knowledge of the inner rotation profile discussed during the workshop organized at Saclay on June 2003 on this topic. In particular we will concentrate on the extraction of the rotational frequency splittings of low- and medium-degree modes and their influence on the rotation of deeper layers. Furthermore, for the first time a full set of individual |m|-component rotational splittings is computed for modes ℓ≤4 and 1<ν<2 mHz, opening new studies on the latitudinal dependence of the rotation rate in the radiative interior. It will also be shown that these splittings have the footprints of the differential rotation of the convective zone which can be extremely useful to study the differential rotation of other stars where only these low-degree modes will be available. Title: Solar gravity modes: the present and future Authors: Turck-Chièze, S.; Garcià, R.; Fossat, E.; Gelly, B.; Palle, P.; Robillot, Jm; Golf-Ng Bibcode: 2004cosp...35.3949T Altcode: 2004cosp.meet.3949T Gravity modes are the best probes to study the solar radiative zone, in particular the nuclear core and to follow its potential variability with time and latitude. Nevertheless, their amplitude is small and the solar noise particularly high in the range of frequency where they stand (below 500 μ Hz). It is why they are looked for more than 20 years and actively serached with GOLF and MDI instruments aboard SoHO which offers the best conditions of observation. Some candidates (Turck-Chièze et al. 2004) have been identified in the GOLF instrument, during the period of low solar activity thanks to an original research of multiplets corresponding to surface amplitudes of about 2mm/s. The examination of the interesting frequency range (100 to 400 μ Hz) will be pursued up to the end of the SoHO mission scheduled for 2007. Today our knowledge of the radiative zone is due to acoustic modes. Recent clear progress is due to the detection of modes less influenced by the sun activity, in the range 400-1600 μ Hz. The sound speed is determined down to 0.06 Ro with a resolution of 3%. This profile is used to improve the solar model and its deviations from a static vision. The rotation profile is now clearly established down to the limit of the core and its rigidity can only be explained by invoking a magnetic field effect. We present here GOLF-NG (Turck-Chièze et al., 2000) built by a French Spanish collaboration to improve g-mode detection. Based on the Doppler velocity method using a resonant spectrometer with a 16 channels on the sodium line, the main objective of GOLF-NG is to contribute to get an MHD picture of the Sun to better understand the influence of the Sun on earth climate, in improving the detection by a factor 10 in decreasing the solar noise thanks to a variable magnet. Consequently, the physical information will be extracted at different heights in the atmosphere. A prototype will be installed in 2005 in Tenerife. Then a spatial version will be available for taking place in one project of the ILWS mission. Turck-Chièze, S., Robillot, J.M., Dzitko, H ., Boumier, P., Decaudin, M., Gabriel, A.H., Garcia, R.A., Grec, G., Pallé, P.L., Renaud, C., Schmidt, D., 2000, ESA SP-464, 331; Turck-Chieze, S., Garcia, R.A., Couvidat, S., et al., 2004, ApJ, vol 604, Title: The Concordia station on Antarctica plateau: the best site on Earth for High Angular Resolution and High Contrast Imaging Authors: Fossat, E.; Aristidi, E.; Agabi, K. Bibcode: 2004EAS....12..125F Altcode: On the Antarctica plateau, a joint project of french and italian polar programmes in just near completion: the Concordia station will be open for winterover operation in 2005. The high altitude and high latitude of this site, the exceptionally cold, clear and stable atmosphere, the almost indefinitely flat snow surface and the not so difficult access make this site the most promising on Earth for future ground based astronomical projects in various fields, including High Angular Resolution and High Contrast Imaging. Title: Solar gravity modes: the present and future Authors: Turck-Chièze, S.; Garcià, R.; Fossat, E.; Gelly, B.; Palle, P.; Robillot, Jm Bibcode: 2004cosp...35.3946T Altcode: 2004cosp.meet.3946T Gravity modes are the best probes to study the solar radiative zone, in particular the nuclear core and to follow its potential variability with time and latitude. Nevertheless, their amplitude is small and the solar noise particularly high in the range of frequency where they stand (below 500 μ Hz). It is why they are looked for more than 20 years and actively serached with GOLF and MDI instruments aboard SoHO which offers the best conditions of observation. Some candidates (Turck-Chièze et al. 2004) have been identified in the GOLF instrument, during the period of low solar activity thanks to an original research of multiplets corresponding to surface amplitudes of about 2mm/s. The examination of the interesting frequency range (100 to 400 μ Hz) will be pursued up to the end of the SoHO mission scheduled for 2007. Today our knowledge of the radiative zone is due to acoustic modes. Recent clear progress is due to the detection of modes less influenced by the sun activity, in the range 400-1600 μ Hz. The sound speed is determined down to 0.06 Ro with a resolution of 3%. This profile is used to improve the solar model and its deviations from a static vision. The rotation profile is now clearly established down to the limit of the core and its rigidity can only be explained by invoking a magnetic field effect. We present here GOLF-NG (Turck-Chièze et al., 2000) built by a French Spanish collaboration to improve g-mode detection. Based on the Doppler velocity method using a resonant spectrometer with a 16 channels on the sodium line, the main objective of GOLF-NG is to contribute to get an MHD picture of the Sun to better understand the influence of the Sun on earth climate, in improving the detection by a factor 10 in decreasing the solar noise thanks to a variable magnet. Consequently, the physical information will be extracted at different heights in the atmosphere. A prototype will be installed in 2005 in Tenerife. Then a spatial version will be available for taking place in one project of the ILWS mission. Turck-Chièze, S., Robillot, J.M., Dzitko, H ., Boumier, P., Decaudin, M., Gabriel, A.H., Garcia, R.A., Grec, G., Pallé, P.L., Renaud, C., Schmidt, D., 2000, ESA SP-464, 331; Turck-Chièze, S., Garcia, R.A., Couvidat, S., et al., 2004, ApJ, vol 604, Title: Solar p modes in 10 years of the IRIS network Authors: Salabert, D.; Fossat, E.; Gelly, B.; Kholikov, S.; Grec, G.; Lazrek, M.; Schmider, F. X. Bibcode: 2004A&A...413.1135S Altcode: IRIS data (the low degree ℓ≤ 3 helioseismology network) have been analysed for the study of p-mode parameters variability over the falling phase of the solar activity cycle 22 and the rising phase of the solar activity cycle 23. The IRIS duty cycle has been improved by the so-called ``repetitive music method'', a method of partial gap filling. We present in this paper an analysis of the dependence of p-mode frequencies and linewidths with frequency and with solar magnetic activity. We confirm also the periodicity of about 70 μHz of the high-frequency pseudo modes, with a much reduced visibility during the phase of higher activity. Title: The Antarctic Planet Interferometer Authors: Swain, M.; Lloyd, J.; Traub, W.; Walker, C.; Stark, A.; Lawson, P.; Storey, J.; Coudé du Foresto, V.; Fossat, E.; Ireland, M.; Burrows, A.; Vakili, F. Bibcode: 2003AAS...203.3815S Altcode: 2003BAAS...35.1262S The Antarctic Planet Interferometer is a concept designed to detect and characterize extrasolar planets by exploiting the unique potential of the best accessible site on Earth for thermal infrared interferometry. High-precision interferometric techniques under development for extrasolar planet detection and characterization (differential phase, nulling and astrometry) all benefit substantially from the slow, low-altitude turbulence, low water vapor content, and low temperatures found on the Antarctic plateau. At the best of these locations, such as the Concordia base being developed at dome C, an interferometer with two-meter diameter class apertures has the potential to deliver unique science for a variety of topics, including extrasolar planets, active galactic nuclei, young stellar objects, and protoplanetary disks. Title: Antarctic site testing: First daytime seeing monitoring at Dome C Authors: Aristidi, E.; Agabi, A.; Vernin, J.; Azouit, M.; Martin, F.; Ziad, A.; Fossat, E. Bibcode: 2003A&A...406L..19A Altcode: The first astronomical seeing monitoring has been made with a DIMM instrument at the Antarctic plateau site of Dome C in December, 2002 on the bright star Canopus (alpha Eri) during the daytime. In these far from optimal conditions, a median seeing value of 1.20 arcsec as been obtained, with extended periods better than 1 arcsec and 12 percent of the time better than 0.75 arcsec. Title: Eleven years of IRIS frequencies and splittings Authors: Fossat, E.; Salabert, David; Cacciani, A.; Ehgamberdiev, S.; Gelly, B.; Grec, G.; Hoeksema, J. T.; Kholikov, S.; Lazrek, M.; Palle, P.; Schmider, F. X.; Tomczyk, S. Bibcode: 2003ESASP.517..139F Altcode: 2003soho...12..139F Having acquired since July, 1989, a complete 11-year solar cycle of full disk data, the IRIS++ network has now made available to anyone the longest helioseismic data base to-date. A few results obtained from this very long time series are briefly presented here, with some emphasis on the low degree p-mode frequencies themselves, and their rotational splittings that have been estimated with unprecedented accuracy. Title: A two color pupil imaging method to detect stellar oscillations Authors: Cacciani, A.; Dolci, M.; Jefferies, S. M.; Finsterle, W.; Fossat, E.; Sigismondi, C.; Cesario, L.; Bertello, L.; Varadi, F. Bibcode: 2003MSAIS...2..172C Altcode: Observations of stellar intensity oscillations from the ground are strongly affected by intensity fluctuations caused by the atmosphere (scintillation). However, by using a differential observational method that images the pupil of the telescope in two colors at the same time on a single CCD, we can partially compensate for this source of atmospheric noise (which is color dependant) as well as other problems, such as guiding and saturation. Moreover, by placing instruments at different locations (eg. Dome C and South Pole) we can further reduce the atmospheric noise contribution by using cross-spectral methods, such as Random Lag Singular Cross-Spectrum Analysis (RLSCA). (We also decrease the likelihood of gaps in the data string due to bad weather). The RLSCA method is well suited for extracting common oscillatory components from two or more observations, including their relative phases. We have evaluated the performance of our method using real data from SOHO. We find that our differential algorithm can recover the absolute amplitudes of the solar intensity oscillations with an efficiency of 70%. We are currently carrying out tests using a number of telescopes, including Big Bear, Mt. Wilson, Teramo and Milano, while waiting for the South Pole and Dome C sites to become available. Title: The Scientific outlook for Astronomy and Astrophysics Research at the CONCORDIA Station Authors: Fossat, Eric; Candidi, Maurizio Bibcode: 2003MSAIS...2....3F Altcode: No abstract at ADS Title: Visible Astronomy as well ? Why not ! Authors: Fossat, Eric Bibcode: 2003MSAIS...2..139F Altcode: It is quite clear that the dry and cold astronomical site of dome C has to be one of the best places on Earth, if not THE best, for infrared and sub millimetric astronomical observations. In comparison with usual observatories located in more usual latitudes, the benefit to be expected in the visible range is a little less obvious. But this benefit does exist indeed. The very long days and nights of the Antarctic plateau provide a unique opportunity for extremely long and nearly uninterrupted observations. Added to the expected reduced amplitude of the stellar scintillation, this makes possible to consider the feasibility of asteroseismic observations that were envisioned only in space so far. Such night time astronomical programmes can be developed very quickly, with moderately sized telescopes, and will benefit of the first winter-over seasons at Concordia. When thinking beyond the first few winters, the unique seeing properties of the site look extremely promising for the combination of interferometry, high performance adaptative optics and stellar coronography, or very high contrast imaging, so that the direct observations of exoplanets must be considered as a possibility for future observations on this site. I briefly review here the first projects and ideas in these directions. As many of these ideas are presented during this "visible" session, you will find details, regarding most of them, in other papers of these proceedings. Title: KEOPS: Kiloparsec Explorer for Optical Planet Search Authors: Vakili, F.; Aristidi, E.; Fossat, E.; Abe, L.; Domiciano, A.; Belu, A.; Agabi, A.; Schmider, F. X.; Lopez, B.; Swain, M. Bibcode: 2003sf2a.conf..365V Altcode: 2003sf2a.confE.165V We present our proposal to develop an imaging optical interferometer at Dome C of Antarctica optimized for both extra-solar planets detection in the thermal infrared and direct astroseismology of nearby stars. The science rationale as well as different steps of technological R&D to make this proposal successful against the adverse conditions of polar nights will be described. Title: The Antarctic Planet Interferometer and the Potential for Interferometric Observations of Extrasolar Planets from Dome C Antarctica Authors: Swain, M. R.; Coudé du Foresto, V.; Fossat, E.; Vakili, F. Bibcode: 2003MSAIS...2..207S Altcode: We present a concept for studying exoplanets using an infrared interferometer with a focused instrument design at the best accessible site on Earth. Title: First daytime seeing monitoring at Dome C Authors: Aristidi, E.; Agabi, A.; Vernin, J.; Azouit, M.; Martin, F.; Ziad, A.; Fossat, E. Bibcode: 2003MSAIS...2..146A Altcode: The first astronomical seeing monitoring has been made with a DIMM instrument at the Antarctic plateau site of Dome C in December, 2002 on the bright star Canopus (alpha Eri) during the daytime. In these far from optimal conditions, a median seeing of 1.2 arcsec as been obtained, with extended periods better than 1 arc-sec and 12 percent of the time better tan 0.75 arcsec. Title: SYMPA: A Dedicated Instrument and a Network for Seismology of Giant Planets Authors: Schmider, F. -X.; Gay, J.; Jacob, C.; Fossat, E.; Valtier, J. -C.; Mosser, B.; Mekarnia, D.; Guillot, T.; Provost, J. Bibcode: 2003aahd.conf..449S Altcode: No abstract at ADS Title: Solar p-modes from 1979 days of the GOLF experiment Authors: Gelly, B.; Lazrek, M.; Grec, G.; Ayad, A.; Schmider, F. X.; Renaud, C.; Salabert, D.; Fossat, E. Bibcode: 2002A&A...394..285G Altcode: With the GOLF instrument onboard the SoHO observatory, 1979 days of full-disc Doppler velocity observations have been compiled into a study of p-mode properties. We develop a multi-step iterative method (MSIM) algorithm to access all p-mode parameters while minimizing any perturbating effect or cross-talk between parameters during their determination. We present frequency and splitting tables, amplitudes, linewidths, line asymmetries, pseudo-modes, and background noise determinations. We have a first look at the changes induced by the transition from the low-activity to the high-activity part of solar cycle 23: we have recorded frequency shifts with a downturn at 3.7 mHz followed by a possible higher upturn, and linewidth changes to a good accuracy. We detect an effect on the noise background at 3 mHz possibly related to an interaction between noise and the modes and connected to the asymmetry of the profiles. Title: IRIS++ database: Merging of IRIS + Mark-1 + LOWL Authors: Salabert, D.; Fossat, E.; Gelly, B.; Tomczyk, S.; Pallé, P.; Jiménez-Reyes, S. J.; Cacciani, A.; Corbard, T.; Ehgamberdiev, S.; Grec, G.; Hoeksema, J. T.; Kholikov, S.; Lazrek, M.; Schmider, F. X. Bibcode: 2002A&A...390..717S Altcode: The IRIS network has been operated continuously since July 1st 1989. To date, it has acquired more than a complete solar cycle of full-disk helioseismic data which has been used to constrain the structure and rotation of the deep solar interior. However, the duty cycle of the network data has never reached initial expectations. To improve this situation, several cooperations have been developed with teams collecting observations with similar instruments. This paper demonstrates that we are able to merge data from these different instruments in a consistent manner resulting in a very significant improvement in network duty cycle over more than one solar cycle initiating what we call the IRIS++ network. The integrated radial velocities from the IRIS++ database (1989 to 1999) are available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/390/717 Title: The concordia station in Antarctica: a real bargain for astronomy? Authors: Fossat, E. Bibcode: 2002sf2a.conf..453F Altcode: No abstract at ADS Title: Variability of p-mode parameters in 11 years of IRIS++ data Authors: Salabert, D.; Jiménez-Reyes, S. J.; Fossat, E.; Gelly, B.; Schmider, F. X. Bibcode: 2002ESASP.508...95S Altcode: 2002soho...11...95S IRIS++ data (the low degrees l <= 3 helioseismologic network) have been analysed for the study of p-modes parameters variability over the solar cycle 22 and the rising phase of cycle 23. This paper discusses the variations of all p-modes parameters along these 11 years. We present the analysis of frequency dependance and time dependance of p-modes frequencies and linewidths. We focus our attention on frequency shifts and their evolution with solar acitivity. We also study the different behaviours between modes of different degrees, and the relation with solar activity indexes. We also discuss periodicities shorter than 1 year which appear in the frequency shifts measurements. Title: p-mode frequencies variability in 15 years of IRIS++ data Authors: Salabert, D.; Jimenez-Reyes, S.; Fossat, E. Bibcode: 2002sf2a.conf..565S Altcode: IRIS++ data (the low degree l >= 3 helioseismology network) have been analysed for the study of p-modes parameters over the solar cycle 22 and the rising phase of cycle 23. This paper discusses the variations of all p-modes parameters along these 11 years. We present the analysis of frequency dependance and time dependance of p-modes frequencies and linewidths. We focus our attention on frequency shifts and study their different behaviours between even and odd modes. We discuss also about periodicities less than 1 year which appear in the frequency measurements. Title: SYMPA: A Specified Instrument and a Dedicated Network for Giant Planets' Sismology Authors: Schmider, F. X.; Gay, Jean; Jacob, Cedric; Fossat, Eric; Valtier, Jean-Claude; Mossier, Benoît; Mekarnia, Djamel; Guillot, Tristan; Provost, Janine Bibcode: 2002sf2a.conf..611S Altcode: The poster I will propose is about the 'SYMPA' project, an instrument dedicated to the study of giant planets interiors, in paricular Jupiter, based on principles of asterosismology. This instrument, developped in collaboration between the department Fresnel of the Observatoire de la Cote d'Azur, and the Laboratoire d'Astrophysique of Nice University, is a Mach-Zender interferometer allowing observations of radial velocities on jovien surface. The poster presents the contribution of sismology to knowledge of planetary interiors, the principle of this new imaging instrument and its performances, and some results from first observations in february and march 2002. Title: 11 years of IRIS network exploitation Authors: Fossat, E.; IRIS Group Bibcode: 2002sf2a.conf..521F Altcode: IRIS, network of 6 stations of integrated sun heliosismic measures, began in 1989 and thus acquired a complete solar cycle of 11 years at the dawn of the 3rd millenium. Being never able to approach enough the crucial rate of 100% coverage, IRIS developed co-operations to exploit other complementary data, and became IRIS++. Having also developed an original method of partial covering of the gaps in the data, which exploits the characteristics of the signal in the Fourier space, the data base IRIS++ reaches finally rates of annual coverage of about 80 to 90%, at the price of some acrobatic treatments which received satisfactory solutions. The average frequencies and splittings of rotation obtained with these 11 years of data can shamelessly be compared with those of space instruments; the rotation, very fine measure which improves with integration time being even better measured by IRIS. If the other parameters of the p modes are less precisely measured by IRIS and if the g modes are inaccessible to it without real hope, alone the frequencies and splittings of the p modes largely justify the investment. Title: Special Session: the future of astronomy at the dome C concordia station in antarctica Authors: Fossat, E. Bibcode: 2002sf2a.conf..449F Altcode: The franco-italian station Concordia will be operational in 2004, and 15 persons could spend winter there. The qualification of the astronomical site and the first observations in infrared imagery and visible photometry are scheduled for the first winters. The potential of this site appears so promising that we must not ignore antarctica in the european large projects propective debate. I will review what is already known, and what we are going to measure to be certain, and speak about collaborations that are being established. Title: Diurnal Atmospheric Extinction Over Oukaïmeden Observatory using IRIS Database: 1989 1997. Comparison With The Other IRIS Sites Authors: Siher, E. A.; Benkhaldoun, Z.; Fossat, E. Bibcode: 2002ExA....13..159S Altcode: In this work, we use data of nine years (1989 to 1997) at allIRIS sites (Culgoora, Kumbel, Oukaïmeden, Izaña, La Silla andStanford, devoted to the study of the solar velocityoscillation) to study of diurnal atmospheric extinctioncoefficient behaviour at Oukaïmeden observatory and to compareit to the others. By this study, we can conclude that the meanextinction coefficient at Oukaimeden is around 0.120 magairmass-1. Besides, we show that the daily extinctioncoefficient varies under the influence of the seasonal effect.By the comparison of Oukaïmeden to the other sites, we showedthat Oukaïmeden has a good photometric sky quality andconstitutes a potential site for astronomical observations inthe north hemisphere. Title: Analysis of variability of p-mode parameters in 11 years of IRIS data Authors: Salabert, D.; Jiménez-Reyes, S. J.; Fossat, E.; Cacciani, A.; Ehgamberdiev, S.; Gelly, B.; Grec, G.; Hoeksema, J. T.; Khalikov, S.; Lazrek, M.; Pallé, P.; Schmider, F. X.; Tomczyk, S. Bibcode: 2002ESASP.477..253S Altcode: 2002scsw.conf..253S 11 years of IRIS (the low degree helioseismology network) have been analysed for the study of p-modes parameters variability. The duty cycle of the network data has been improved by the partial gap filling method named "repetitive music". This paper discusses the variations of all p-modes parameters along these 11 years. Title: The Concordia Antarctic Station: an opportunity for asteroseismology and planetary search Authors: Schmider, F. X.; Fossat, E.; Vernin, J.; Martin, F.; Azouit, M.; Agabi, K.; Clausse, J. M.; Grec, G. Bibcode: 2002ESASP.485..219S Altcode: 2002sshp.conf..219S Interruption in the obervations is a main limitation for asteroseismology. It conducted to the development of networks and spacecraft for asteroseismology as for helioseismology. However, the continuity offered by polar locations has played an historical role in the development of helioseismology, allowing the first measurement of individual mode frequencies (Fossat et al. 1981). Several projects were in the past envisioned for the exploitation of this capability for stellar observations, but none of them were actually developed. From 2004, the permanent Antarctic station Concordia, will be running for its first winter season. Located at Dome C, the Franco-Italian station will hold several scientific programs, including glaciology, geophysics, meteorology and astronomy. Continuity of the observations is not the only advantage of the polar station for astronomy. The high altitude, the low temperature and the incredible dryness of the site make it very favorable for sub-mm and far IR observations. The Nice University has already started the qualification of the site in the visible domain. Up to now, no night data has been recorded yet about sky transparency and seeing. However, they are good reasons to expect exceptional conditions. In comparison with South Pole site, the location on a dome provides very quiet weather with almost no wind. In consequence, the seeing, mainly dominated at South Pole by ground layer, should be excellent. Moreover, the absence of high altitude jet-stream let expect a scintillation much lower than in any other place. This would allow CCD observations to detect very faint photometric variations as expected for asteroseismology, or planetary detection. Title: Spectral analysis of solar diameter measurements recorded at Calern Observatory astrolabe during two solar cycles Authors: Moussaoui, R.; Irbah, A.; Fossat, E.; Borgnino, J.; Laclare, F.; Delmas, C.; Schmider, F. X. Bibcode: 2001A&A...374.1100M Altcode: Solar diameter measurements performed with the Calern Observatory astrolabe (O.C.A - France) during more than two solar cycles show temporal variations. Due to the weather, seasonal effects and instrumental characteristics, recorded solar data are non uniformly sampled and present temporal gaps. Thus, to analyze these data, diameter measurements averaged over one or more months have generally been considered. This limits the accessible harmonic terms to a low frequency range. To determine short-term periodicities from the observed variations, all daily solar data need to be considered and also corrected from the zenithal distance. In the present work, we use two methods to analyze solar diameter measurements recorded at Calern Observatory astrolabe during the observation period 1975-1996. They are based on least square fits and deconvolution of the observation window function. Results deduced from the analysis confirm harmonic terms already found by other authors but also reveal new higher frequencies. Title: An estimation of global solar p-mode frequencies from IRIS network data: 1989-1996 Authors: Serebryanskiy, A.; Ehgamberdiev, Sh.; Kholikov, Sh.; Fossat, E.; Gelly, B.; Schmider, F. X.; Grec, G.; Cacciani, A.; Palle, P. L.; Lazrek, M.; Hoeksema, J. T. Bibcode: 2001NewA....6..189S Altcode: The IRIS network has accumulated full disk helioseismological data since July 1989, i.e. a complete 11-year solar cycle. Since the last paper publishing a frequency list [A&A 317 (1997) L71], not only has the network acquired new data, but has also developed new co-operative programs with compatible instruments [Abstr. SOHO 6/GONG 98 Workshop (1998) 51], so that merging IRIS files with these co-operative program data sets has made possible the improvement of the overall duty cycle. This paper presents new estimations of low degree p-mode frequencies obtained from this IRIS++ data bank covering the period 1989-1996, as well as the variation of their main parameters along the total range of magnetic activity, from before the last maximum to the very minimum. A preliminary estimation of the peak profile asymmetries is also included. Title: GOLF data analysis using a whole spectrum fitting method: temporal variations in 1445 days of the GOLF velocity signal Authors: Lazrek, M.; Gelly, B.; Grec, G.; Renaud, C.; Fossat, E.; GOLF Team Bibcode: 2001ESASP.464..523L Altcode: 2001soho...10..523L The analysis of 1445 days of GOLF signal provides a first quick-look to the solar cycle effects on the low order low-degree modes detected by this instrument. Title: An Estimation of Global p-mode Frequencies and Splitting from the IRIS Network Data: 1989-1996 Authors: Ehgamberdiev, Sh. A.; Serebryanskiy, A. V.; Khalikov, Sh. S.; Fossat, E.; Gelly, B.; Teem, Iris Bibcode: 2001IAUS..203...97E Altcode: The IRIS network has accumulated low-l modes data since July, 1989, i.e. one complete solar cycle. Since the last publication of a frequency table (in 1997) the IRIS data bank was not only filled with new data, but also has been supplemented with data from other helioseismology instruments, through cooperative programs. The results of a new estimations of frequencies and splitting obtained with the resulting increase of the global duty cycle, as well as their variation along the solar magnetic activity cycle will be presented. Title: Analysis of Diameter Measurements Performed at Calern Observatory Astrolabe Authors: Moussaoui, R.; Irbah, A.; Abdelatif, T.; Fossat, E.; Borgnino, J.; Laclare, F.; Delmas, C. Bibcode: 2000SoPh..195..433M Altcode: Solar diameter measurements performed at Calern Observatory astrolabe during more than two solar cycles show variations at various time scales in a broad range. Due to seasonal effects and instrumental characteristics, the recorded data are not sampled uniformly and present some gaps during these years. This time series has been analyzed by means of a deconvolution of the window function, as an alternative method to the standard least square fits of harmonic functions. The results show an extremely important improvement of the power spectrum. Harmonic terms already found by other authors are confirmed but new frequencies are also revealed by this analysis. Title: Full disk helioseismology: repetitive music and the question of gap filling Authors: Fossat, E.; Kholikov, Sh.; Gelly, B.; Schmider, F. X.; Fierry-Fraillon, D.; Grec, G.; Palle, P.; Cacciani, A.; Ehgamberdiev, S.; Hoeksema, J. T.; Lazrek, M. Bibcode: 1999A&A...343..608F Altcode: Helioseismology requires continuous measurements of very long duration, months to years. This paper addresses the specific and limited case of full disk measurements of p-mode oscillations, although it can be generalized, to some extent, to the case of imaged helioseismology. First, a method of mode by mode (or rather pair of modes by pair of modes) interpolation of the signal in gaps is tested, and shown to be efficient for gaps as long as two days, but limited to the frequency range where the signal to noise ratio is good. It is then noted that the autocorrelation function of the full disk signal, after dropping quickly to zero in 20 or 30 minutes, shows secondary quasi periodic bumps, due to the quasi-periodicity of the peak distribution in the Fourier spectrum. The first of these bumps, at 4 hours or so, is higher than 70 percent and climbs to nearly 90 percent in limited frequency ranges. This suggests that an easy gap filling method can be developed, with a confidence of nearly 90 percent across all the frequency range, as long as the gap does not exceed 8 hours, with at least 4 hours of data at both ends. Even a short gap of one or two periods is better filled by the data taken 4 hours earlier or later than by local interpolation. This relaxes quite considerably the requirement of continuity of the observations for the case the full disk p-mode helioseismology. Applied to 7 years of IRIS data, this method permits the detection of all low frequency p-modes already seen by 2 years of the GOLF instrument data, and makes possible the measurement of their frequencies with an accuracy consistent with the partially filled 7 years of statistics. Title: On the Capability of Ground Based Networks to Precisely Estimate the Solar Background in Full Disk Helioseismology Authors: Fossat, E.; Kholikov, Sh.; IRIS Team Bibcode: 1999ASPC..173..309F Altcode: 1999sstt.conf..309F No abstract at ADS Title: Power spectrum modelisation of helioseismic data: an application to the measurement of solar p-mode uncertainties Authors: Fierry Fraillon, D.; Gelly, B.; Schmider, F. X.; Hill, F.; Fossat, E.; Pantel, A. Bibcode: 1998A&A...333..362F Altcode: We estimate the statistical uncertainties of low-l solar p-modes parameters based on a Monte Carlo approach. Random perturbations of ideal Lorentz profiles L(a nu _i) can provide many estimations of the set of p-modes parameters a and allow one to estimate statistical error-bars sigma_ {a} by modelling the parameters' distribution function. Unlike frequencies, which show symmetric distributions, amplitudes and linewidths have asymmetric probability density function similar to the distribution function for time-averaged energies of stochastically excited solar p-modes (Kumar, 1988). A comparison between sigma_ ν and uncertainties based on Hessian's computation (Libbrecht 1992, Toutain and Appourchaux 1994) shows a nice agreement. However, our error-bars take into account more statistical effects, and rely less on the initial parameters' estimation. Such a technique has been used on the IRIS power spectra computed from gapped data, and on one GONG power spectrum computed from almost continuous data. We also present IRIS linewidths and error bars averaged over the years 1989-92 and computed with a fitting strategy using imposed frequency which improves the value of both the parameter and its uncertainty. Title: Cross-Correlation Technique in Individual Splitting Determination Authors: Fierry Fraillon, D.; Lazrek, M.; Fossat, E.; Gelly, B.; Golf Team Bibcode: 1998ESASP.418..161F Altcode: 1998soho....6..161F We review here the cross-correlation technique applied to the individual splitting measurement in Golf data. We perform the cross-correlation of the same multiplet taken from two different power spectra: in the ideal situation, the result is looking like a triplet of Lorentzian for l = 1 (5 for l = 2 and 7 for l = 3) with a constant separation given by the splitting (Lazrek et al. 1996). We use a continuous time serie of 18-months Golf data, whith no frequency shift due to the solar cycle (Fierry Fraillon et al. 1998), and we can then produce 6 differents realisations of the same multiplet corresponding to a 3-months spectral resolution. A sidereal value of the splitting is then deduced for each n,l modes using the average of the corresponding 15 cross-correlations. The results show the independence of the splitting as a function of the order n, and the agreement with a rigid solar core rotation. Title: First Results on it P Modes from GOLF Experiment Authors: Lazrek, M.; Baudin, F.; Bertello, L.; Boumier, P.; Charra, J.; Fierry-Fraillon, D.; Fossat, E.; Gabriel, A. H.; García, R. A.; Gelly, B.; Gouiffes, C.; Grec, G.; Pallé, P. L.; Pérez Hernández, F.; Régulo, C.; Renaud, C.; Robillot, J. -M.; Roca Cortés, T.; Turck-Chièze, S.; Ulrich, R. K. Bibcode: 1997SoPh..175..227L Altcode: The GOLF experiment on the SOHO mission aims to study the internal structure of the Sun by measuring the spectrum of global oscillations in the frequency range 10-7 to 10-2 Hz. Here we present the results of the analysis of the first 8 months of data. Special emphasis is put into the frequency determination of the p modes, as well as the splitting in the multiplets due to rotation. For both, we show that the improvement in S/N level with respect to the ground-based networks and other experiments is essential in achieving a very low-degree frequency table with small errors ∼ 2 parts in 10-5). On the other hand, the splitting found seems to favour a solar core which does not rotate slower than its surface. The line widths do agree with theoretical expectations and other observations. Title: Performance and Early Results from the GOLF Instrument Flown on the SOHO Mission Authors: Gabriel, A. H.; Charra, J.; Grec, G.; Robillot, J. -M.; Roca Cortés, T.; Turck-Chièze, S.; Ulrich, R.; Basu, S.; Baudin, F.; Bertello, L.; Boumier, P.; Charra, M.; Christensen-Dalsgaard, J.; Decaudin, M.; Dzitko, H.; Foglizzo, T.; Fossat, E.; García, R. A.; Herreros, J. M.; Lazrek, M.; Pallé, P. L.; Pétrou, N.; Renaud, C.; Régulo, C. Bibcode: 1997SoPh..175..207G Altcode: GOLF in-flight commissioning and calibration was carried out during the first four months, most of which represented the cruise phase of SOHO towards its final L1 orbit. The initial performance of GOLF is shown to be within the design specification, for the entire instrument as well as for the separate sub-systems. Malfunctioning of the polarising mechanisms after 3 to 4 months operation has led to the adoption of an unplanned operating sequence in which these mechanisms are no longer used. This mode, which measures only the blue wing of the solar sodium lines, detracts little from the detection and frequency measurements of global oscillations, but does make more difficult the absolute velocity calibration, which is currently of the order of 20%. Data continuity in the new mode is extremely high and the instrument is producing exceptionally noise-free p-mode spectra. The data set is particularly well suited to the study of effects due to the excitation mechanism of the modes, leading to temporal variations in their amplitudes. The g modes have not yet been detected in this limited data set. In the present mode of operation, there are no indications of any degradation which would limit the use of GOLF for up to 6 years or more. Title: Solar P-mode frequencies from the IRIS network. Authors: Gelly, B.; Fierry-Fraillon, D.; Fossat, E.; Palle, P.; Cacciani, A.; Ehgamberdiev, S.; Grec, G.; Hoeksema, J. T.; Khalikov, S.; Lazrek, M.; Loudagh, S.; Pantel, A.; Regulo, C.; Schmider, F. X. Bibcode: 1997A&A...323..235G Altcode: The Iris network for helioseismology has operated since 1989. We present tables of solar p-mode frequencies for observations taken during the four summer seasons from 1989 to 1992. This analysis uses the technique of maximum likelihood fitting and a χ_2_^2^ model for the probability density function of the spectrum. The simultaneous fitting of odd and even pairs of peaks strengthens the identification of the l=3 eigenmodes and improves the error bars on the 0-2 group. The frequencies are in good agreement with other observational results and with theoretical values for the D_0_ and the {DELTA}ν parameters of the asymptotic approximation. A decrease of 0.25+/-0.12μHz is seen between the 1989 and the 1992 data sets. The change is associated with the decrease of solar activity and is comparable with results of previous studies. Title: New IRIS constraints on the solar core rotation. Authors: Gizon, L.; Fossat, E.; Lazrek, M.; Cacciani, A.; Ehgamberdiev, S.; Gelly, B.; Grec, G.; Hoeksema, J. T.; Khalikov, S.; Palle, P. L.; Pantel, A.; Regulo, C.; Schmider, F. -X.; Wilson, P. R. Bibcode: 1997A&A...317L..71G Altcode: Four time series of IRIS data (4 to 6 months) have been used to obtain improved measurements of the low degree (l=1,2,3) rotational splitting frequencies. Assuming that the rotation law is known in the outer layers of the Sun, we investigate the implications of IRIS splittings for the central regions. Both a one-shell and a two-shell rotation model have been considered in the solar core. A core rotating slightly faster than the outer radiative envelope provides the best fit to the data. Some evidence for the reliability of the observations is shown by the visibility of differential rotation in the l=3 multiplets. Title: Performance and first results from the GOLF instrument on SoHO Authors: Gabriel, A. H.; Charra, J.; Grec, G.; Robillot, J. -M.; Roca Cortés, T.; Turck-Chièze, S.; Ulrich, R.; Baudin, F.; Bertello, L.; Boumier, P.; Decaudin, M.; Dzitko, H.; Foglizzo, T.; Fossat, E.; García, R. A.; Herreros, J. M.; Lazrek, M.; Pallé, P. L.; Pétrou, N.; Renaud, C.; Régulo, C. Bibcode: 1997IAUS..181...53G Altcode: No abstract at ADS Title: Three years of ANTENA: what we have done! Authors: Belmonte, J. A.; Hernández, M. M.; Pérez Hernández, F.; Vidal, I.; Roca Cortés, T.; Michel, E.; Auvergne, M.; Chevreton, M.; Goupil, M. J.; Soufi, F.; Baglin, A.; Frandsen, S.; Viskum, M.; Kjeldsen, H.; Christensen-Dalsgaard, J.; Schmider, F. X.; Fossat, E.; Delache, Ph.; Provost, J.; Audard, N.; Berthomieu, G.; Paparó, M.; Kovács, G.; Szabados, L. Bibcode: 1997IAUS..181..357B Altcode: No abstract at ADS Title: Philippe Delache (8 October 1937 - 1994). Authors: Fossat, E. Bibcode: 1997IAUS..181D..27F Altcode: No abstract at ADS Title: GOLF results: today's view on the solar modes Authors: Grec, C.; Turck-Chièze, S.; Lazrek, M.; Roca Cortés, T.; Bertello, L.; Baudin, F.; Boumier, P.; Charra, J.; Fierry-Fraillon, D.; Fossat, E.; Gabriel, A. H.; Garcia, R. A.; Gelly, B.; Gouiffes, C.; Régulo, C.; Renaud, C.; Robillot, J. M.; Ulrich, R. K. Bibcode: 1997IAUS..181...91G Altcode: No abstract at ADS Title: Is the Solar Core Rotating Faster of Slower Than the Envelope? Authors: Lazrek, M.; Pantel, A.; Fossat, E.; Gelly, B.; Schmider, F. X.; Fierry-Fraillon, D.; Grec, G.; Loudagh, S.; Ehgamberdiev, S.; Khamitov, I.; Hoeksema, J. T.; Pallé, P. L.; Régulo, C. Bibcode: 1996SoPh..166....1L Altcode: The Sun is not a rigid body and it is well known that its surface rotation is differential, the polar regions rotating substantially slower than the equator. This differential rotation has been demonstrated by helioseismology to continue down to the base of the convective zone, below which it becomes closer to a rigid body rotation. Far deeper, inside the energy generating core, the rotation has generally been assumed to be much faster, keeping memory of the presumably high speed of the young Sun. However, several recent results of helioseismology have decreased this likelihood more and more, so that the core rotation could be suspected to be only marginally, or even not at all faster than the envelope. Certain results would even imply a core rotation slower than the envelope, an interesting but unlikely possibility. We present here a complete analysis of the rotational splitting of the low degree modes measured in three different time series obtained in 1990, 1991, and 1992 by the IRIS full-disk network. With a time of integration slightly longer than 4 months, the splitting has been measured by 4 different global methods on 42 doublets of l= 1, 35 triplets of l = 2, and 30 quadruplets of l = 3. With a high level of confidence, our result is consistent with a rigid solar core rotation. Title: Global Oscillations at Low Frequency from the SOHO Mission (GOLF) Authors: Gabriel, A. H.; Grec, G.; Charra, J.; Robillot, J. -M.; Roca Cortés, T.; Turck-Chièze, S.; Bocchia, R.; Boumier, P.; Cantin, M.; Cespédes, E.; Cougrand, B.; Crétolle, J.; Damé, L.; Decaudin, M.; Delache, P.; Denis, N.; Duc, R.; Dzitko, H.; Fossat, E.; Fourmond, J. -J.; García, R. A.; Gough, D.; Grivel, C.; Herreros, J. M.; Lagardère, H.; Moalic, J. -P.; Pallé, P. L.; Pétrou, N.; Sanchez, M.; Ulrich, R.; van der Raay, H. B. Bibcode: 1995SoPh..162...61G Altcode: The GOLF experiment on the SOHO mission aims to study the internal structure of the sun by measuring the spectrum of global oscillations in the frequency range 10−7 to 10−2 Hz. Bothp andg mode oscillations will be investigated, with the emphasis on the low order long period waves which penetrate the solar core. The instrument employs an extension to space of the proven ground-based technique for measuring the mean line-of-sight velocity of the viewed solar surface. By avoiding the atmospheric disturbances experienced from the ground, and choosing a non-eclipsing orbit, GOLF aims to improve the instrumental sensitivity limit by an order of magnitude to 1 mm s−1 over 20 days for frequencies higher than 2.10−4 Hz. A sodium vapour resonance cell is used in a longitudinal magnetic field to sample the two wings of the solar absorption line. The addition of a small modulating field component enables the slope of the wings to be measured. This provides not only an internal calibration of the instrument sensitivity, but also offers a further possibility to recognise, and correct for, the solar background signal produced by the effects of solar magnetically active regions. The use of an additional rotating polariser enables measurement of the mean solar line-of-sight magnetic field, as a secondary objective. Title: P-Mode Frequencies of Degree L = 3 TO 5 Authors: Pantel, A.; Hoeksema, T.; Fossat, E.; Scherrer, P.; Gelly, B.; Grec, G.; Loudagh, S.; Schmider, F. X. Bibcode: 1995ESASP.376b.381P Altcode: 1995soho....2..381P; 1995help.confP.381P No abstract at ADS Title: Solar Core Rotation: Latest IRIS Results Authors: Fossat, E.; Lazrek, M.; Loudagh, S.; Pantel, A.; Gelly, B.; Grec, G.; Schmider, F. X.; Pallé, P. L.; Régulo, C.; Ehgamberdiev, S.; Khalikov, S.; Hoeksema, T. Bibcode: 1995ESASP.376b.261F Altcode: 1995help.confP.261F; 1995soho....2..261F No abstract at ADS Title: Solar P-Mode Frequencies from the IRIS Network Authors: Gelly, B.; Fossat, E.; Palle, P.; Appourchaux, T.; Eghamberdiev, S.; Fierry-Fraillon, D.; Grec, G.; Hoeksema, J. T.; Khalikov, S.; Lazrek, M.; Loudagh, S.; Pantel, A.; Regulo, C.; Sanchez, L.; Schmider, F. X. Bibcode: 1995ESASP.376b.373G Altcode: 1995help.confP.373G; 1995soho....2..373G No abstract at ADS Title: Philippe Delache, 1937 - 13 October 1994. Authors: Barlier, F.; Bonnet, R. M.; Fossat, E.; Leibacher, J.; Frisch, U. Bibcode: 1995JAF....47....2B Altcode: No abstract at ADS Title: IRIS Status Repport Authors: Fossat, E. Bibcode: 1995ASPC...76....7F Altcode: No abstract at ADS Title: IRIS Data Merging and Deconvolution Authors: Pantel, A.; Fossat, E. Bibcode: 1995ASPC...76..496P Altcode: 1995gong.conf..496P No abstract at ADS Title: A New TEchnology Network for Asteroseismology - A.N.T.E.N.A. Authors: Roca Cortes, T.; Belmonte, J. A.; Delache, P.; Michel, E.; Frandsen, S.; Schmider, F. X.; Auvergne, M.; Fossat, E.; Vidal, I.; Kjeldsen, H.; Douglas, N.; Lelievre, G.; Chevreton, M.; Vauclair, G.; Audard, N.; Baglin, A.; Berthomieu, G.; Christensen-Dalsgaard, J.; Dolez, N.; Goupil, M. J.; Perez Hernandez, F.; Pfeiffer, B.; Provost, J.; Viskum, M. Bibcode: 1995ASPC...76..630R Altcode: 1995gong.conf..630R No abstract at ADS Title: On the Solar Core Rotation - IRIS Results Authors: Fossat, E.; Loudagh, S.; Gelly, B.; Grec, G.; Pantel, A.; Provost, J.; Berthomieu, G.; Ehgamberdiev, S.; Khalikov, S.; Lazrek, M.; Palle, P. L.; Regulo, C. Bibcode: 1995ASPC...76...24F Altcode: 1995gong.conf...24F No abstract at ADS Title: On the Solar Core Rotation - IRIS Results Authors: Fossat, E.; Loudagh, S.; Gelly, B.; Grec, G.; Panel, A.; Provost, J.; Berthomieu, G.; Ehgamberdiev, S.; Khalikov, S.; Lazrek, M.; Palle, P. L.; Regulo, C. Bibcode: 1995ASPC...76....4F Altcode: No abstract at ADS Title: Working Group 20 - Low-degree p-mode Rotational Splittings and Solar Core Rotations Authors: Fossat, E. Bibcode: 1995ESASP.376a.229F Altcode: 1995heli.conf..229F No abstract at ADS Title: IRIS Status Report Authors: Fossat, E. Bibcode: 1995ASPC...76..387F Altcode: 1995gong.conf..387F No abstract at ADS Title: Test of a Differential Photometer for Extinction Gradient Correction in Full-Disk Helioseismology Authors: Khatami, M.; Fossat, E. Bibcode: 1994ExA.....4..253K Altcode: The ground based full disk velocity Doppler measurements used in helioseismology suffer from an atmospheric noise component when the sky transparency is not perfect. It is due to the non uniform integration of the line of sight component of the solar rotation produced by the differential atmospheric extinction across the direction of the solar equator. A simple two-channel differential photometer is proposed for measuring this differential extinction. The first laboratory tests of this instrument show that it has the capability of performing the required correction without adding a significant level of new instrumental noise contribution. Title: On scintillation obfuscation Authors: Badiali, M.; Catala, C.; Fossat, E.; Fransden, S.; Gough, D. O.; Rocca-Cortes, T.; Schrijver, K. Bibcode: 1994Obs...114...53B Altcode: No abstract at ADS Title: Solar Oscillations: Full Disk Observations from the Geographic South Pole Authors: Grec, G.; Fossat, E.; Pomerantz, M. Bibcode: 1994snft.book..410G Altcode: No abstract at ADS Title: Full-disk helioseismic IRIS raw data calibration. Authors: Palle, P. L.; Fossat, E.; Regulo, C.; Loudagh, S.; Schmider, F. X.; Ehgamberdiev, S.; Gelly, B.; Grec, G.; Khalikov, S.; Lazrek, M.; Sanchez, L. Bibcode: 1993A&A...280..324P Altcode: The International Research on the Interior of the Sun (IRIS) helioseismometer measures the full disk line of sight velocity of the Sun. In fact, it makes a photometric mesurement using two monochromatic spectral windows located on the wings of the D1 solar line. This is a non-linear measurement. Before a scientific exploitation of the IRIS data, the instrumental signal must be converted from non-linear photometric data into calibrated line of sight velocity. In this process, it is necessary to extract the small component due to the solar surface motions from the much larger contributions of the Earth spin, the Earth orbit, the gravitational redshift, the D1 line distortions produced by solar activity and even some telluric atmospheric effects. This paper describes the calibration method which is now used for pre-processing the IRIS data. It is the result of several iterations, and the use of one and a half years of IRIS data from one instrument, at Teide Observatory. It is certainly the best possible method to date, given the quality of the current data, and it can be regarded as valid over all the entire p-mode frequency range, and down to 100 microHz or so in the g-mode range. At lower frequencies, calibration, solar noise and merging techniques cannot be completely separated, and possible further improvements are still under investigation. Title: Modeling of integrated sunlight velocity measurements: The effect of surface darkening by magnetic fields Authors: Ulrich, R. K.; Henney, C. J.; Schimpf, S.; Fossat, E.; Gelly, B.; Grec, G.; Loudagh, S.; Schmider, F. -X.; Palle, P.; Regulo, C. Bibcode: 1993A&A...280..268U Altcode: It has been known since the work by Claverie et al. (1982) that integrated-sunlight velocities measured with the resonance scattering technique show variations with time scales of weeks to months. The cause can be understood in terms of the effects of solar activity as was pointed out by Edmunds & Gough (1983) and Andersen & Maltby (1983). The latter authors included a model calculation based on sunspot areas which showed good promise of being able to quantitatively reproduce the observed velocity shifts. We discuss in this paper a new modeling effort based on daily magnetograms obtained at the 150-ft tower on Mt. Wilson. This type of database is more quantitative than sunspot area. Similar maps of magnetically sensitive quantities will be measured on a continuous time base as part of several planned helioseismology experiments (from space with the Solar Oscillations Imagery/Michelson Doppler Imager (SOI/MDI) experiment on the Solar and Heliospheric Observatory (SOHO), see Scherrer et al. (1991) or with ground-based networks, see Hill & Leibacher (1991)). We discuss the correlations between various magnetically sensitive quantities and develop a new model for the effects of magnetic field on line profiles and surface brightness. From these correlations we integrate the line profile changes over the solar surface using observed magnetic field strengths measured at lambda 5250.2. The final output is a new model for the effects of magnetic fields on integrated sunlight velocities which we compare with daily offset velocities derived from the International Research on the Interior of the Sun (IRIS)-T instrument at the Observatorio del Teide. Title: The solar interior Authors: Turck-Chièze, S.; Däppen, W.; Fossat, E.; Provost, J.; Schatzman, E.; Vignaud, D. Bibcode: 1993PhR...230...57T Altcode: This report confronts the different aspects of the solar interior from the experimental and theoretical points of view, discussing photospheric abundances, neutrinos and acoustic mode measurements. The theoretical approach mainly concerns the classical framework of stellar evolution, nevertheless, particle interpretation of the data and astrophysical solutions invoked in the last 10 years are coherently examined. Title: A measurement of the I = I solar rotational splitting Authors: Loudagh, S.; Provost, J.; Berthomieu, G.; Ehgamberdiev, S.; Fossat, E.; Gelly, B.; Grec, G.; Khalikov, S.; Lazrek, M.; Palle, P.; Regulo, C.; Sanchez, L.; Schmider, F. -X. Bibcode: 1993A&A...275L..25L Altcode: A precise measurement of the l = 1 rotational splitting has been derived from the 1991 IRIS data and it leads to a moderate rotation rate in the solar core. Title: On Full Disk Helioseismology Power Spectra around the Cut-Off Frequency Authors: Regulo, C.; Fossat, E.; Roca-Cortes, T.; Ehgamberdiev, S.; Gelly, B.; Grec, G.; Khalikov, S.; Lazrek, I. Khamitov M.; Palle, P. L.; Sanchez-Duarte, L. Bibcode: 1993ASPC...42..103R Altcode: 1993gong.conf..103R No abstract at ADS Title: On the acoustic cut-off frequency of the sun Authors: Fossat, E.; Regulo, C.; Roca Cortes, T.; Ekhgamberdiev, S.; Gelly, B.; Grec, G.; Khalikov, S.; Khamitov, I.; Lazrek, M.; Palle, P. I. Bibcode: 1992A&A...266..532F Altcode: Full solar disk observations of radial velocity, obtained with the IRIS network of resonant scattering spectrometers, are used to analyze the acoustic p-mode spectrum around the acoustic cut-off frequency. Three different methods are used to determine it; two use the power spectrum, while the third uses the phase spectrum. The three values measured converge to a common value of 5.55 +/- 0.1 mHz, which is higher than any theoretical prediction. Beyond this frequency, the power spectra still decreases down to 10 mHz at which point it becomes flat, showing the presence of some power due to the so-called pseudomodes which we show are the result of interference between traveling waves. The acoustic power density measured beyond the cut-off frequency makes it possible to estimate the energy deposited into the chromosphere about 10 exp 7 erg/sq cm per sec, which is high enough to compensate the losses that take place in this layer. Title: IRIS data merging. I. A solution to minimize the low and intermediate frequency noise. Authors: Fossat, E. Bibcode: 1992A&A...263..443F Altcode: Time series of artificial low frequency noise have been produced to simulate the instrumental and atmospheric noise in the full solar disk measurements. They have been used to test various possible methods of merging data obtained simultaneously at different sites with different instruments operated under different sky conditions, with the goal of minimizing the nonsolar noise level in the 0.02-1 mHz frequency range. A merging method is proposed which implies a continuous window function deconvolution and then a loss of information on the velocity signal itself, but which proves to be far superior with respect to noise level. Title: Amplitude modulation of low-degree solar p-modes Authors: Egamberdiev, S.; Khalikov, S.; Lazrek, M.; Fossat, E. Bibcode: 1992A&A...253..252E Altcode: Due to the combined effect of varying interference between unresolved individual p-modes and the true amplitude modulation of these p-modes, the power spectrum obtained over one day of full-disk helioseismic data varies strongly from day to day. The statistical distribution of power within a given peak has accordingly been studied as a function of modulation-amplitude magnitude. The result obtained is dependent on the level of interdependence of the amplitude fluctuations displayed by the various individual modes. Two independent, converging values are obtained for the amplitude modulation. Title: Possible detection of Jovian global oscillations Authors: Schmider, F. -X.; Fossat, E.; Mosser, B. Bibcode: 1991A&A...248..281S Altcode: Observations of the Jupiter were carried out using a refined version of the stellar seismometer with a sensitivity of better than 50 cm/s. The observations revealed the existence of strong velocity variations of the planets in the 10-20-min period range. It is concluded that the observed variations can only be explained as global acoustic modes. The frequencies of the modes are examined with reference to the internal structure of the planet. Title: Global oscillation measurements at Kumbel station in frame of the IRIS programme Authors: Baijumanov, A.; Ehgamberdiev, Sh.; Fossat, E.; Grec, G.; Ilyasov, S.; Kamaldinov, A.; Khalikov, Sh.; Khamitov, I.; Manigault, J. F.; Menshikov, G.; Raubaev, S.; Yuldashbaev, T. Bibcode: 1991SoPh..133...51B Altcode: The second of the IRIS network instruments was commissioned in August 1988 at Kumbel mountain, located 75 km from Tashkent (U.S.S.R.). Atmospheric and operating conditions on Kumbel are discussed, as well as preliminary results derived from this station's global solar oscillation measurements. Title: Preface Authors: Fossat, Eric Bibcode: 1991SoPh..133D...7F Altcode: No abstract at ADS Title: The IRIS sodium cell instrument Authors: Grec, G.; Fossat, E.; Gelly, B.; Schmider, F. X. Bibcode: 1991SoPh..133...13G Altcode: In the framework of the IRIS programme, full-disk solar Doppler-shift measurements are made with an optical resonance sodium cell spectrophotometer, a new pattern of the instrument successfully used at the geographic South Pole 10 years ago. After many successive improvements, the IRIS version has now become a precise and reliable device, being limited only by the solar and/or by the atmospheric noise in all the frequency ranges of interest for the p-mode and the g-mode investigation. This instrument is described here in some detail, with the technical specification for each individual component being defined by comparison to the photon and the solar noise. Title: The IRIS Network for Full Disk Helioseismology - Present Status of the Programme Authors: Fossat, Eric Bibcode: 1991SoPh..133....1F Altcode: IRIS (International Research on the Interior of the Sun) is the name of a worldwide network of 8 observing stations for full disk helioseismology. The IRIS scientific community is organizing a yearly workshop in one of the 8 sites. This paper is the introduction to the proceedings of the second IRIS workshop, held at Tashkent, Uzbekistan SSR. It presents a brief history, the structure of the international cooperation, the membership rule, the list of sites and members, the scientific working teams additional structure and, as an appendix, the report of the first meeting of the IRIS Scientific Committee. Title: General Presentation of a Single IRIS Site Raw Data Analysis Problem Authors: Egamberdiev, Sh.; Khalikov, S.; Fossat, Eric Bibcode: 1991SoPh..133...69E Altcode: A complete software package has been built for the calibration in m s −1 of the velocity residuals due to solar oscillations in the raw IRIS (International Research on the Interior of the Sun) data. It takes into account all known astronomical components contributing to the line-of-sight velocity between the instrument and the solar surface, and also the apparent velocity due to the non-uniform integration of the solar rotation as seen through an inhomogeneous Earth atmosphere. The IRIS data itself is used for the estimation of the nonlinear instrumental response to the velocity, and the residual can be directly obtained in velocity units, without low frequency filtering. On a day of typical photometric sky quality, the power spectrum obtained appears to be solar noise limited. Title: The Second IRIS Workshop. Proceedings. 2. IRIS (International Research on the Interior of the Sun) Workshop, Tashkent, Uzbekistan SSR (USSR), Sep 1989. Authors: Egamberdiev, Sh.; Fossat, Eric Bibcode: 1991SoPh..133.....E Altcode: Papers are presented on the IRIS (for International Research on the Interior of the Sun program) sodium cell instrument, the IRIS data management, global oscillation measurements at Kumbel Station in frame of the IRIS program, the Moroccan participation in the study of solar oscillations, and the general presentation of a single IRIS site raw data analysis problem. Attention is given to some peculiarities of the power spectrum of the 5-min solar brightness oscillations, new results on the 160-min pulsation of the sun, 5-min variations of the global magnetic field of the sun, the instrumental capabilities of the Sayan Observatory for the study of oscillatory processes on the sun, and a standard solar model of the asymptotic spectrum of gravity modes as a function of the solar structures. Other papers are on solar convective zone and acoustic oscillations and seismic probing of outer regions of the sun. Title: Héliosismologie: observations. Authors: Fossat, E. Bibcode: 1991sed..conf...23F Altcode: Contents: (1) Introduction. (2) Les observables. (3) Les observations. (4) Paramètres à mesurer. (5) Le problème du temps d'intégration. (6) Les programmes d'observation actuels. (7) A propos de la précision des mesures. (8) Sélection de quelques résultats récents et de problèmes en suspens parmi d'autres. (9) En guise de conclusion provisoire. (10) IRIS status report. Title: Jovian Seismology Authors: Mosser, B.; Gautier, D.; Fossat, E.; Schmider, F. -X.; Delache, Ph.; Gay, J.; Mekarnia, D. Bibcode: 1990BAAS...22.1065M Altcode: No abstract at ADS Title: The IRIS network for full disk helioseismology. full disk helioseismology. Present status of the programme Authors: Schmider, Francois-Xavier; Fossat, Eric; Gelly, Bernard; Grec, Gérard Bibcode: 1990LNP...367..241S Altcode: 1990psss.conf..241S I.R.I.S.(International Research on the Interior of the Sun) is the name of a worldwide network of 8 stations of observation in full disk helioseismology. The I.R.I.S. scientific community is organizing a yearly workshop in one of the 8 sites. This paper presents the status of the network as it was for the second IRIS workshop, held at Tashkent, Uzbekistan SSR, in September 1989. It presents a brief history, the structure of the international cooperation, the membership rule, the list of sites and members, the scientific working teams additional structure and, as an appendix, the report of the first meeting Title: Full-disk Helioseismology in the Antarctic Authors: Fossat, E.; Gelly, B.; Grec, G.; Schmider, F. -X. Bibcode: 1990AIPC..198..231F Altcode: 1989AIPC..198..231F; 1990asan.conf..231F The South Pole has been an important site for unimaged helioseismology since 1979. With the rapid development of helioseismology, observations have evolved toward international network and space projects. Future observations from the South Pole will have an important role in validating data from low-latitude networks, obtained certain measurements comparable only to those made in space and for imaged disk data. The utility of the South Pole could be enhanced by combining measurements ufrom the pole and at another Antarctic station such as Dome C. Title: Seismological Study of Procyon and Arcturus Authors: Schmider, F. X.; Fossat, E. Bibcode: 1989BCFHT..21...15S Altcode: No abstract at ADS Title: Searching for solar g-modes, tests of a statistical method. Authors: Fossat, Eric; Grec, Gerard; Gavrjusev, Vladimir; Gavrjuseva, Elena Bibcode: 1988ESASP.286..393F Altcode: 1988ssls.rept..393F The solar g-modes are extremely difficult to detect because of their very small amplitude and because of the absence of any regular pattern in their frequency distribution. A frequency dependent noise power spectrum and a g-mode power spectrum can look extremely similar. The authors propose to use crosscorrelation and autocorrelation methods to test the presence of g-modes in a real power spectrum. This method is used on 3 years of ACRIM irradiance data with negative conclusion. It is also tested with synthetic g-modes computed into a standard and a non standard model. Only the standard model seems to offer enough regularity in rotational splitting and in period separation to make reliable the measurement of these two parameters. Title: Effects of convective velocities on solar pressure mode frequencies. Authors: Delache, Philippe; Fossat, Eric Bibcode: 1988ESASP.286..671D Altcode: 1988ssls.rept..671D There are persistent discrepancies between observations and theoretical calculations of solar p-mode frequencies, νobs, νcalc, in spite of improvements in the theory (e.g. equation of state). In this short communication, the authors propose to approximate roughly the difference (observation-calculation) versus frequency as: δν = νobs-νcalc ≍ -Kν2, where the constant K is of the order of 1 second, and independent of degree l. It has been already suggested by T. Brown that "Solar p-mode eigenfrequencies are decreased by turbulent convection". The authors want to revisit this suggestion and reformulate it in the following manner: is this physical effect responsible for some of the difference ν0-νcalc? After a brief discussion of the mechanism, the authors present an order of magnitude evaluation which shows that, indeed, it is worthwhile to pursue the idea further: this will be done in improving the description of the coupling between convection and oscillations. Title: Solar calibration of asteroseismology. Authors: Gelly, B.; Fossat, Eric; Grec, Gerard; Schmider, F. X. Bibcode: 1988ESASP.286..579G Altcode: 1988ssls.rept..579G The first expected result of asteroseismology will consist in the measurement of two parameters, Δν and D0, which in the Tassoul's asymptotic approximation are close to the sound speed integral across the solar radius, and to the sound speed gradient inside the nuclear burning core, respectively. The first depends mostly on the mass and evolves slowly with age, while the second is strongly age dependant through the increase of molecular mass in the stellar core. Theorists have started to built Δν - D0 diagrams, as a tool for the determination of mass and age of stars. For a precise calibration of such a diagram the authors have made a precise measurement of those parameters in the case of the sun. Title: Solar p-modes frequency variations between 1980 and 1986. Authors: Gelly, B.; Fossat, Eric; Grec, Gerard Bibcode: 1988ESASP.286..275G Altcode: 1988ssls.rept..275G Using a method of power spectra cross-correlation, the authors were able in 1986 to confirm a 0.39 μHz decrease of solar low degree p-mode frequencies between 1980 and the end of 1984. With the same method applied to the 1984/85 South Pole data and to all the ACRIM data obtained until april 1986, they again confirm the value of this decrease. Moreover, they find an extreme stability of these frequencies from spring 1984 to spring 1986 with a relative accuracy of 0.02 μHz. Title: The Nice University stellar seismometer. Authors: Schmider, F. X.; Fossat, Eric; Grec, Gerard; Gelly, B. Bibcode: 1988ESASP.286..605S Altcode: 1988ssls.rept..605S The authors' instrument devoted to stellar seismology uses a Cacciani-type sodium cell as a very stable frequency reference for radial velocity measurements. It was successfully operated for the detection of oscillations on Procyon and Alpha Centauri in 1983 and 1984. In a new version, its sensitivity has been inreased and the sources of noise have been reduced. The authors give a brief description of the principle and discuss the limits of sensitivity. Other possible applications are also suggested. Finally they discuss the capabilities of this instrument in the context of the developement of asteroseismology. Title: I.R.I.S.: a network for full disk helioseismology. Authors: Fossat, Eric Bibcode: 1988ESASP.286..161F Altcode: 1988ssls.rept..161F Presented in 1983 to the french "Institut National des Sciences de l'Univers", the I.R.I.S. (for Installation d'un Réseau International de Sismologie Solaire in french, or International Research on the Interior of the Sun, in english) project was first funded in 1984 by this Institute. It consists in the deployment of 7 observing stations in full-disk helioseismology, distributed in complementary longitudes and latitudes. This paper is a short presentation of the sites, teams, and calendar of this network. Title: Modelling the solar oscillation time series by a randomly excited oscillator. Authors: Lazrek, Mohamed; Delache, Philippe; Fossat, Eric Bibcode: 1988ESASP.286..673L Altcode: 1988ssls.rept..673L If the individual solar oscillations were pure standing waves of constant amplitude inside a stationary Sun, there would be in principle no intrinsic limits to the accuracy with which their frequencies could be measured. Unfortunately, it is not so. In their analysis of 10 months of irradiance data from the SMM/ACRIM experiment, Woodard and Hudson have proposed to describe the individual modes as independent and chaotically excited oscillators, the linewidths being of the order of 1.2 μHz in the central frequency range, around 3 mHz. This paper deals with artificial full disk data. The goal is to determine the parameters of a randomly excited oscillator by comparison with the best data available. Such artificial signal is then used to test the methods of analysis used for the precise determination of mode frequencies, amplitudes and linewidths. The authors present tests of the reliability of centroid measurements made by barycenter, Lorentzian fit, Gaussian fit, with and without background noise. Several methods are also tested for linewidth measurements. Title: GOLF: Global Oscillations at Low Frequencies for the SOHO mission Authors: Gabriel, A. H.; Bocchia, R.; Bonnet, R. M.; Cesarsky, C.; Christensen-Dalsgaard, J.; Dame, L.; Delache, Ph.; Deubner, F. L.; Foing, B.; Fossat, E. Bibcode: 1988sohi.rept...13G Altcode: The GOLF (global oscillations at low frequencies) SOHO (solar heliospheric observatory) mission is described. It aims to study the internal structure of the Sun by measuring the spectrum of free global oscillations. GOLF will measure both p and g mode oscillations, with emphasis on low order long period waves which penetrate the solar core. The instrument aims to measure frequencies between 10-7 and 6 10-3 Hz, with a sensitivity of 1 mm/s. The method involves an extension to space of the ground based technique for measuring the mean line-of-sight velocity of the solar surface. A sodium vapor resonance scattering filter is used in a longitudinal magnetic field to sample the two wings of the solar absorption line. The use of a modulating magnetic field provides a continuous internal calibration of the sensitivity. By adding an additional rotating polarizer, measurements are also made of the average solar magnetic field. Efforts are made to correct the data for the spurious effects caused by solar magnetic active regions. Title: Solar calibration of asteroseismology Authors: Gelly, B.; Grec, G.; Schmider, F. -X.; Fossat, E. Bibcode: 1988A&A...200..207G Altcode: The first expected result of asteroseismology will consist in the measurement of two parameters, Δν and D0. The first depends mostly on the mass and evolves slowly with age, while the second is strongly age dependent through the increase of molecular mass in the stellar core. Theorists have started to build Δν - D0 diagrammes, as a tool for the determination of mass and age of stars. The authors have made a precise measurement of those parameters in the case of the sun. D0 appears to be consistent, within the here published error bar of 2%, with the frequency tables of the most recent standard models. This is an extremely severe constraint to be satisfied by every eventual non-standard model. Title: New analysis of the solar p-mode frequency change from 1980 to 1986 Authors: Gelly, B.; Fossat, E.; Grec, G. Bibcode: 1988A&A...200L..29G Altcode: Using a method of power spectra cross-correlation, the authors were able in 1986 to confirm a 0.39 μHz decrease of solar low degree p-mode frequencies between 1980 and the end of 1984. With the same method applied to their 1984/85 south pole data and to all Acrim data obtained until April 1986, they again confirm this decrease, and on the other hand, they find an extreme stability of these frequencies from spring 1984 to spring 1986, with an accuracy of 0.02 μHz. Title: Evidence for Global Pressure Oscillations in Procyon and Alpha-Centauri Authors: Gelly, B.; Grec, G.; Fossat, E. Bibcode: 1988IAUS..123..249G Altcode: For the full paper see Abstr. 42.116.003. Title: Seismology of the Stellar Cores Authors: Fossat, E. Bibcode: 1988IAUS..132..209F Altcode: No abstract at ADS Title: Helioseismology from the South Pole - the 1984/85 Campaign Authors: Gelly, B.; Fossat, E.; Grec, G.; Pomerantz, M. Bibcode: 1988IAUS..123...21G Altcode: More than 700 hours of full disk line of sight solar velocity have been recorded at the Geographic South Pole between late November 1984 and early February 1985. This paper presents very briefly some preliminary results of the analysis of this data. Title: Sodium Cell Spectrophotometer for Detection of Stellar Oscillations Authors: Schmider, F. X.; Fossat, E.; Grec, G.; Gelly, B. Bibcode: 1988IAUS..123..513S Altcode: This paper describes a new version of the authors' instrument used for detection of stellar oscillations. It is planned to use it next year for observations of Procyon and α Cen in order to confirm the results already obtained. Title: Multi-year variations of solar oscillations Authors: Fossat, Eric Bibcode: 1988AdSpR...8g.107F Altcode: 1988AdSpR...8..107F Several solar oscillation time series exist now which are of enough quality and duration for making possible an investigation of possible long term variations of p-mode frequencies. The intrinsic accuracy on the determination of an individual frequency is estimated by means of the best available p-mode lifetime measurements. A statistical estimation of the accessible amplitude of long term frequency drifts is deduced. With an optimum integration time of the order of 6 months, it is shown to be as small as 0.03 μ Hz. A critical review of results published to-date in this investigation is then presented and discussed. Title: Search for Solar P-Mode Frequency Changes Between 1980 and 1985 Authors: Fossat, E.; Gelly, B.; Grec, G.; Pomerantz, M. Bibcode: 1987A&A...177L..47F Altcode: 704 hours of solar full disk velocity measurements obtained at the South Pole between the end of November, 1984 and early February, 1985 have been analyzed. The p-mode power spectrum of this data and that obtained in 1980 with the SMM / ACRIM instrument are compared by a cross-correlation method. Taking into account the small bias in the analysis due to the different window functions and to the different relative responses to modes of degree 0 to 3, a frequency decrease of 0.39 μHz is found, with an uncertainty estimated at 0.04 μHz. Title: Evidence for global pressure oscillations in Procyon and alpha Centauri. Authors: Gelly, B.; Grec, G.; Fossat, E. Bibcode: 1986A&A...164..383G Altcode: Helioseismology has proved to be a powerful tool to probe the internal structure of the sun. With a new adapted optical-resonance spectrophotometer, an extension has been attempted to two bright stars, namely Alpha Cen A and Procyon. Results obtained from two observing runs on Alpha Cen A in May 1983 and May 1984 at La Silla, and one observing run on Procyon in February 1984 at Hawaii are presented. In both cases, solarlike pressure oscillations have been detected. The complete analysis determines essentially five parameters: the frequency range, the amplitudes, the mean equidistance, the departure around this equidistance (curvature of the echelle-diagram), and the fine frequency spacing between modes of degree 0 and 2. For Procyon, all results are consistent with theoretical predictions, including excitation of oscillations, mass, radius, and age of the star. For Alpha Cen, all the results are consistent together and are confirmed by the 1984 observations. They suggest that Alpha Cen A might be younger than estimated, which is consistent with a ZAMS star. Title: Evidence for p-modes on Alpha Centauri and Procyon. Authors: Fossat, E.; Gelly, B.; Grec, G. Bibcode: 1986ASIC..169..405F Altcode: 1986ssds.proc..405F Helioseismology has proved to be a powerful tool to probe the internal structure of the Sun. With a new adapted optical resonance spectrophotometer, an extension has been attempted to Alpha Centauri A and Procyon. In both cases, solar-like pressure oscillations have been detected. The complete analysis is presented, which leads to determine essentially five parameters: the mean equidistance Δν, the frequency range, the amplitudes, the departure around equidistance (curvature of the Echelle diagram) and the fine frequency spacing between modes of degrees 0 and 2. Title: Global Oscillations Authors: Fossat, E. Bibcode: 1985ESASP.235..209F Altcode: 1985fmsh.work..209F; 1985shpp.rept..209F It is now possible to probe the solar models and the solar rotation over more than 60% of the outer solar radius. Some significant disagreement remains between observation and theory, and the author concentrates his presentation on the discussion of the already obtained and expected future benefits of full disk measurements in this quest for the best possible fit. Title: Advances in Solar Seismology at the South Pole Authors: Pomerantz, M. A.; Fossat, E.; Gelly, B.; Grec, C.; Harvey, J. W.; Duvall, T. L. Bibcode: 1985AnJUS..20..221P Altcode: No abstract at ADS Title: Solar observations at the South Pole. Authors: Fossat, E.; Grec, G. Bibcode: 1985BCSAB..71..177F Altcode: No abstract at ADS Title: Atmospheric limitations in stellar seismology: Should one measure radial velocity or brightness fluctuations? Authors: Fossat, E. Bibcode: 1984NASCP2350...68F Altcode: 1984itp..work...68F Low degree p-modes of the Sun have been measured in spatially integrated sunlight (the Sun as a star) both in Doppler shift and in intensity fluctuations. These observations are a good starting point for the discussion of the best way to collect equivalent data on other stars. It is assumed that the Sun is removed far enough in space to become an ordinary star of magnitude zero to one. Evidently another star will oscillate with different frequencies and different amplitudes, but some reference must be made to start with. Using this scheme, a detailed investigation of the limitations of observational accuracy in the search for global p-modes is made. The sources of noise stand in the Sun itself, in the instrumentation, in the observing time duration, in the corpuscular nature of the light and mostly in the Earth atmosphere in the case of ground based observations. Title: Five-minute P modes detected in Doppler shift measurement on Alpha Centauri Authors: Fossat, E.; Grec, G.; Gelly, B. Bibcode: 1984NASCP2350...28F Altcode: 1984itp..work...28F A spectrophotometer using the principle of optical resonance spectroscopy, designed for the goal of identifying radial and weakly non radial eigenmodes in the five minute range in the case of stars, is discussed. The conclusion of the first test of this new instrument was that if the observation can be photon noise limited (i.e., in total absence of any instrumental source of noise), the five-minute solar oscillation could still be detected by removing the Sun far enough for its magnitude to become zero or one. Such a situation is very closely represented by the observation of Alpha Centauri A, because it is a G2 V star, very similar to the Sun, with a mass of 1.1 in solar unit. Six nights were granted to this program on a 3.6m telescope, from 22 to 28 May 1983. Two and half nights provided over 20 hours of data of photometric quality good enough for analysis. Title: Solar large scale velocity structures from optical resonance method Authors: Robillot, J. M.; Bocchia, R.; Fossat, E.; Grec, G. Bibcode: 1984A&A...137...43R Altcode: Preliminary observations have been made to search for large scale velocity fields by means of sodium optical resonance spectrophotometry. The authors recall that the standard method measures only 2 points of the line, in order to derive the Doppler shift. They point out an ambiguity from line profile distortion, because apparent upflows are seen in the wide area of active regions. In any case, this can explain the long-term modulation observed in full disk Doppler measurements (Claverie et al., 1982) without the need of invoking a rapidly rotating core. In the quiet solar atmosphere, an upper limit of 15 m s-1 rms for the large scale (≥50,000 km) velocity distribution is deduced. A relatively simple optimization of the optical resonance technique is suggested in order to progress in this field. Title: Detection des oscillations de pression sur alpha du Centaure. Authors: Fossat, E.; Grec, G.; Gelly, B.; Decanini, Y. Bibcode: 1984CRASB.299...17F Altcode: 1984CR2...299...17F; 1984CRSPH.299...17F; 1984CRASM.299...17F Optical resonance spectrophotometry was used to scan Alpha Centauri (G2V) for evidence of oscillations. Data were taken over six nights in May 1983 with a 3.6 m telescope. The results comprised the monochromatic intensity in the red region of the Na D1 and D2 lines and the total intensity at 20 A centered on the D lines. A Fourier transform analysis of the data in terms of frequency and phase revealed a 5 min period similar to that exhibited by the sun. The periodic structure appeared between 3-3.5 MHz and had a period of 80 micro-Hz, and were close in frequency and structure to solar p-modes. Implications of the discovery for analysis of convective forces and the composition of the two stars are discussed. Title: Stellar seismology - Five-minute P modes detected on Alpha Centauri Authors: Fossat, E.; Grec, G.; Gelly, B.; Decanini, Y. Bibcode: 1984Msngr..36...20F Altcode: A spectrophotometer was devised for detecting seismic disturbances in stellar sources. Based on the principle of optical resonance spectroscopy, the instrument is capable of 1/msec oscillation amplitude Doppler shift measurements. Twenty hours of data on Alpha Centauri covered the monochromatic intensity in the red wings of Na D1 and D2 lines and a 20 A passband of an interference prefilter used in a reference channel. Steps were taken to account for atmospheric interference and determine the harmonics using Fourier analysis. An 81.3 micro-Hz period was observed for a 2.3-3.8 mHz periodicity in the power spectrum, a result that is similar to a period detected in the Sun, thereby indicating that a 5 min p-mode may also be occurring in Alpha Centauri. Title: Low degree p-modes observed in velocity and brightness Future in the frame of the space-ground competition Authors: Fossat, E. Bibcode: 1984MmSAI..55...47F Altcode: Observational data on low-degree p-mode solar oscillations are summarized, and observational techniques to provide further information are discussed in detail. The specific advantages of full-disk, center/outer-annulus, and two-dimensional-imaging observations are indicated; the need for longer time series to determine the lifetimes of amplitude and phase modes, their frequency variation, the fine structure of individual power-spectrum peaks, and the nature of the 160-min oscillation is stressed; stellar p-modes are considered; and the sources of noise in ground-based and spaceborne observations (photon noise, telescope guiding, apparatus instability, scintillation, and transparency changes) are examined. It is found that both solar and stellar Doppler-signal observations are already photon-noise-limited from the ground, but the quality of solar-brightness measurements and broadband photometry of stars can be greatly improved from space. Title: Five-minute P Modes Detected in Doppler Shift Measurement on Alpha Centauri Authors: Fossat, E.; Gelly, B.; Grec, G. Bibcode: 1984LIACo..25..229F Altcode: 1984trss.conf..229F; 1984tpss.conf..229F No abstract at ADS Title: Solar Oscillations (text not received) Authors: Fossat, E. Bibcode: 1984faa..conf...69F Altcode: No abstract at ADS Title: Should One Measure Radial Velocity or Brightness Fluctuations Authors: Fossat, E. Bibcode: 1984srps.conf...77F Altcode: Low degree p-modes of the sun have been measured in spatially integrated sunlight both in Doppler shift and intensity fluctuations. The guideline of this paper is to assume that the sun is removed far enough in space to become an ordinary star of magnitude zero to one. Evidently, another star will oscillate with different frequencies and different amplitudes, but one must use some reference to start with. With this scheme, a detailed investigation of the limitations of observational accuracy in the search for global p-modes is made. The sources of noise stand in the sun itself, in the instrumentation, in the observing time duration, in the corpuscular nature of the light and mostly in the earth atmosphere (for ground-based observations). Finally, a detection of five minute p-modes on α Cen are reported. Title: First Test of the New Spectrophotometer Devoted to Stellar Seismology Authors: Fossat, E.; Decanini, Y.; Grec, G. Bibcode: 1983Msngr..33...29F Altcode: Solar seismology (or helioseismology) was born in 1975. Since that recent date it provided the first unambiguous information regarding the internal structure of the sun. Title: Full-Disk Observations of Solar Oscillations from the Geographic South-Pole - Latest Results Authors: Grec, G.; Fossat, E.; Pomerantz, M. A. Bibcode: 1983SoPh...82...55G Altcode: 1983IAUCo..66...55G This paper presents the latest results obtained from the analysis of the full-disk Doppler shift observations obtained at the geographic South Pole in 1981. About 80 normal modes of oscillation (l = 0-3) have now been identified. Their frequencies range from 1886 μHz (l = 1, n = 12) to 5074.5 μHz (l = 2, n = 35), and their amplitudes are as low as 2.5 cm s-1. Amplitude modulation occurs with periods of 1-2 days, and the individual oscillations appear to be excited randomly and independently. In cases where other groups have observed some of the modes identified by us, the agreement in frequency is good. Title: A spectrophotometer devoted to stellar seismology. Authors: Fossat, E.; Decanini, Y.; Grec, G. Bibcode: 1982ASSL...92..169F Altcode: 1982IAUCo..67..169F; 1982ialo.coll..169F An overview of stellar seismology observation techniques is given, stressing a new instrument developed in Italy. A solar spectrophotometric method, requiring high sensitivity and high temporal resolution, has identified 75 various modes of oscillation. This method can be improved by performing more observations from the Antarctic and from space, and it is also proposed that similar observations of different stars may be useful in understanding the theory of stellar evolution. A proposed technique for making such observations uses optical resonance. A beam is transmitted through sodium vapor, between two crossed linear polarizers. A Wollaston prism can be used to replace the entrance polarizer, in order to utilize both directions of polarization. It appears that the photon efficiency of this instrument is comparable to other spectroscopic techniques, but it has the advantage of the high spectral stability of the optical resonance. Title: Solar Pulsations Observed from the Geographic South Pole - Initial Results Authors: Fossat, E.; Grec, G.; Pomerantz, M. Bibcode: 1981SoPh...74...59F Altcode: Initial results of round-the-clock observations of solar oscillations at the South Pole are briefly summarized by describing the Figures 1 to 4. Title: Atomic Beam and Optical Resonance Cells Authors: Fossat, E.; Grec, G. Bibcode: 1981siwn.conf..135F Altcode: No abstract at ADS Title: Solar Pulsations: Report from the Antarctic Authors: Fossat, E.; Grec, G.; Pomerantz, M. Bibcode: 1981siwn.conf..385F Altcode: No abstract at ADS Title: Solar and stellar oscillations. Authors: Fossat, E. Bibcode: 1981ASIC...68...75F Altcode: 1981spss.conf...75F An introduction is provided to the field of solar and stellar seismology, which uses observations of global pulsations as probes of the interior structures of the sun and stars. The nature of stellar or solar oscillations is discussed, and the restoring forces and excitation mechanisms involved in the establishment of the oscillations are identified. Observational data needed to constrain theoretical models of stellar and solar oscillations is indicated, and the primary methods by which this information is obtained are presented, including Doppler shift measurements, measurements of intensity fluctuations and astrometry. Some of the most important results of solar seismology are presented, including the resolution of the five-minute ridges, and observations of solar diameter oscillations, radial and low-l modes in the five-minute range, and long-period solar oscillations. Potentials for the observation and identification of small-amplitude nonradial oscillations on nonvariable stars other than the sun are also noted. Title: When the Sun vibrates. Authors: Fossat, E. Bibcode: 1981Rech...12.1280F Altcode: No abstract at ADS Title: Solar oscillations: full disk observations from the geographic South Pole Authors: Grec, G.; Fossat, E.; Pomerantz, M. Bibcode: 1980Natur.288..541G Altcode: Observing conditions at the geographic South Pole enable modes of global solar oscillations and theoretical models of the internal solar structure to be identified. Title: Shaking Down the Sun's Long-Period Vibes Authors: Kotov, V. A.; Severny, A. B.; Tsap, T. T.; Scherrer, P. H.; Wilcox, J. M.; Fossat, E.; Grec, G.; Pomerantz, M. Bibcode: 1980SciN..118..100K Altcode: No abstract at ADS Title: Solar Seismology: A New View from the South Pole Authors: Pomerantz, M. A.; Grec, G.; Fossat, E. Bibcode: 1980AnJUS..15..200P Altcode: No abstract at ADS Title: Comment about phase coherence of solar diameter pulsations. Authors: Grec, G.; Fossat, E. Bibcode: 1979MNRAS.188P..21G Altcode: No abstract at ADS Title: Solar pulsations and angular coherence of atmospheric transparency fluctuations. Authors: Grec, G.; Brandt, P.; Fossat, E.; Duebner, F. L. Bibcode: 1979A&A....77..347G Altcode: It is noted that radial-velocity measurements in integrated sunlight are contaminated by atmospheric noise due to inhomogeneous transparency of earth's atmosphere along the line of sight to the solar disk. A measurement of the angular autocorrelation function of slow fluctuations in atmospheric transparency is described. It is shown that the typical coherence size is about 1 deg and independent of fluctuation amplitudes of 0.7 percent to 30 percent and that the angular autocorrelation function provides a link between global transparency variations and spurious measured velocities. It is concluded that all ground-based full-disk Doppler measurements should be carefully interpreted because atmospheric noise is present for periods greater than 5 min and less than about 90 min. Title: Calculation of pseudo narrow band oscillations produced by atmospheric differential extinction. Authors: Grec, G.; Fossat, E. Bibcode: 1979A&A....77..351G Altcode: It is suggested that diurnal effects due to the atmospheric transparency may give rise to systematic drift in solar Doppler measurements. The effect of differential atmospheric transparency on measurements is investigated. It is shown to favour harmonic 8, 9, and 10 for measurement durations from 4 to 10 h. This effect can explain an amplitude close to 1 m/s for these harmonics, and also the appearance of phase coherence over long time periods. Title: The sun, a variable star. Authors: Fossat, E.; Souffrin, P. Bibcode: 1978Rech....9..526F Altcode: The paper describes supergranules in the solar surface and a local oscillation with a 5-minute frequency in the solar atmosphere. The supergranules can be approximately 30 times the size of the granules and are more stable than the granules, the supergranules persisting more than 10 hours, that is, more than 100 times the lifetime of a granule. While the existence of two systems - granules and supergranules - can not yet be explained by convection theory, the horizontal movements in the supergranules do explain the reticular structure of the solar magnetic field, as the movement from the center to the edge of the supergranule drags the magnetic field to the border. The local oscillations extend a distance of a few thousand meters and persist approximately 20 minutes. The implications of supergranules and local oscillation for an understanding of the external layers of stars are discussed. Title: Experiments for large multi-mirror telescopes. I.- Detection of non radial stellar oscillations. Authors: Roddier, F.; Fossat, E.; Grec, G.; Roddier, C. Bibcode: 1978otf..conf..357R Altcode: Preliminary measurements made with a 2-m telescope equipped with a sodium cell have shown that nonradial oscillations similar to the solar 5-min oscillations could be detected on bright stars with an integration time of three hours and a 5-m telescope. Because of their aberrations, large optical telescopes of the future will act as light collectors rather than imaging devices. An analysis demonstrates how interferometric techniques can be used to obtain good images with a multi-mirror telescope. Title: Atmospheric Effects in Long Period Pulsation Studies Authors: Fossat, E.; Grec, G. Bibcode: 1978pfsl.conf..151F Altcode: 1978ESPM....2..151F No abstract at ADS Title: Photospheric oscillations. IV. An accurate omega -spectrum at low values of k. Authors: Fossat, E.; Grec, G.; Slaughter, C. Bibcode: 1977A&A....60..151F Altcode: Two spatiotemporal (k - omega) power spectra of the solar five-minute oscillation are calculated with a resolution of 0.3 mHz for an 8.5-ft and a 36-in. aperture, respectively. The two spectra are found to appear almost identical except in the low-frequency range, where differences arise due to large amounts of atmospheric noise. An average omega-spectrum is determined from the two power spectra and is compared with a previously computed power spectrum. It is concluded that for wavenumbers (k) not exceeding 0.0001 per km, the dependence of the unresolved omega-spectrum on wavenumber is fairly weak and that the average of the two spatiotemporal power spectra can be regarded as a good estimate of the unresolved omega-spectrum for any wavenumber bandwidth in the range from 0 to 0.0001 per km. Title: Apparent solar oscillations and fluctuations in the earth's atmosphere. Authors: Fossat, E.; Harvey, J.; Hausman, M.; Slaughter, C. Bibcode: 1977A&A....59..279F Altcode: Measurements of air mass fluctuations are presented and interpreted with a simple model. Such fluctuations can produce a spectrum of apparent solar diameter fluctuations similar in magnitude with the spectrum of observed apparent solar diameter fluctuations. Title: Photospheric Oscillations. III. Search for Long Period Modes Authors: Grec, G.; Fossat, E. Bibcode: 1977A&A....55..411G Altcode: Summary. The stability of the sodium optical resonance device has been optimised for the study of long period solar pulsations. Observations are made on the integrated solar light, which are insensitive to guiding errors. The residual five-minute oscillation is clearly observed with a r.m.s. amplitude of about 2 m s `. The low frequency spectrum is carefully examined in the range of periods between five minutes and 1.5 h, with a sensivity of 70 cm s `. After subtraction of the slow drifts, the data are treated by standard Fourier analysis and time correlations. It is shown that the power spectra never rise above the statistical significance level. It is concluded that solar oscillations, if they exist, must have an amplitude smaller than 70 cm s - in integrated light. Key words: sun - photosphere oscillations - long period modes Title: A spectrophotometer for the study of long period solar photospheric oscillations. Authors: Grec, G.; Fossat, E.; Vernin, J. Bibcode: 1976A&A....50..221G Altcode: The paper describes a sodium optical resonance photoelectric spectrophotometer for measuring the Doppler shifts of the Na D1 line in the solar photosphere. The photometer operates on the basis of absorption of the spectral windows corresponding to the sigma Zeeman components. Problems of sensitivity (photon noise, guiding, residual modulation due to clouds) are considered, and the optimization of the spectrophotometer for the study of long period photospheric oscillations is discussed. A sensitivity of 1 m/s is expected for a velocity field integrated over the spectral range 0-1 MHz. Title: TECHNOLOGIE: Mechanicals deformation studies of astronomical instrument using interferometric method Authors: Ricort, G.; Aime, C.; Fossat, E. Bibcode: 1976NROpt...7...63R Altcode: An interferometric method which permits the precise measurement of the instantaneous mechanical deformation of a telescope as a function of any parameter (weight, vibration, heating, etc.) is described. Two small mirrors fixed at the telescope aperture are illuminated by a laser from the focus of the instrument, and the resulting interference fringes are observed microscopically. Mechanical deformation of the instrument results in a motion of the fringes in the plane of observation. The technique has been used to measure the flexure of the Nice Coude telescope. The thermal stabilization time was found to be about 20 min. A continuous deformation as a function of the hour angle, corresponding to fringe motion at about 1 arc sec/min, was observed. Title: Observations of the Line-Of-Sight Velocity Authors: Fossat, E. Bibcode: 1976IAUTB..16..244F Altcode: 1976IAUT...16B.244F No abstract at ADS Title: Photospheric oscillations. II - Acoustic filtering in the solar atmosphere and heating of the chromosphere Authors: Fossat, E.; Ricort, G. Bibcode: 1975A&A....43..253F Altcode: Summary. Intensity fluctuations in the wings of the Fraunhofer line Na D t 5896 have been recorded for about two hundred hours at the focus of the Nice coude' refractor, using a sodium optical resonance device. Because of the large beam aperture available, records have been made on circular apertures from 22" up to 32' diameter (the whole sun). The principal results from the analysis of these data are: - As shown by White and Cha (t973), the five-minute oscillation has a gaussian random character with a mean lifetime of about 20 min. Its two-dimensional spatial power spectrum is roughly gaussian for every temporal frequency between 2 and 6 MHz. The width of this gaussian spectrum is near 5 t0- km -1 (i.e. 2 = 20000 km). It is shown that this value corresponds to a cellular pattern having a "coherence scale" near 5000 km. Various results published since 1962 concerning this coherence scale become consistent by taking a unified definition of this scale. - A new oscillatory mode of to min period has been discovered, for photo spheric apertures larger than 3' It does not appear to have the random gaussian character of the 5-min mode, but seems to be a spasmodical phenomenon, both in space and time. Key words: optical resonance photo spheric oscillations Title: Photospheric oscillations. I. Large scale observations by optical resonance method. Authors: Fossat, E.; Ricort, G. Bibcode: 1975A&A....43..243F Altcode: Summary. Intensity fluctuations in the wings of the Fraunhofer line Na D t 5896 have been recorded for about two hundred hours at the focus of the Nice coude' refractor, using a sodium optical resonance device. Because of the large beam aperture available, records have been made on circular apertures from 22" up to 32' diameter (the whole sun). The principal results from the analysis of these data are: - As shown by White and Cha (t973), the five-minute oscillation has a gaussian random character with a mean lifetime of about 20 min. Its two-dimensional spatial power spectrum is roughly gaussian for every temporal frequency between 2 and 6 MHz. The width of this gaussian spectrum is near 5 t0- km -1 (i.e. 2 = 20000 km). It is shown that this value corresponds to a cellular pattern having a "coherence scale" near 5000 km. Various results published since 1962 concerning this coherence scale become consistent by taking a unified definition of this scale. - A new oscillatory mode of to min period has been discovered, for photo spheric apertures larger than 3' It does not appear to have the random gaussian character of the 5-min mode, but seems to be a spasmodical phenomenon, both in space and time. Key words: optical resonance photo spheric oscillations Title: Statistical analysis of a plate corrected for photographic noise. Authors: Ricort, G.; Aime, C.; Fossat, E. Bibcode: 1974A&A....37..105R Altcode: The paper describes a statistical analysis method for the correction, for photographic noise, of the spatial power spectrum of the density fluctuations of a photospheric solar granulation plate. It is assumed that the photographic noise is statistically independent of the signal. If this noise is ignored, any spatial frequency is overestimated. Increasing the size of the spot is inefficient, because, although the photographic noise is reduced at the highest frequencies, nothing is changed for all the lower frequencies of the signal. Signal/noise discrimination can be made using the difference in spread of the two spectra. The method requires the investigation of a zone of uniform density. The shape of the autocorrelation function of the photographic noise is obtained using an exploring spot small enough not to cut off too much of the high frequencies of the photographic noise. The plate is then investigated with the same exploring spot, and the subtraction of the photographic noise is made at the autocorrelation function. Title: Evidence for Large-Scale Oscillations of the Solar Photosphere Authors: Fossat, E.; Ricort, G.; Aime, C.; Roddier, F. Bibcode: 1974ApJ...193L..97F Altcode: Doppler shifts of the Na D1 line, averaged over large solar areas up to the whole sun, have been recorded with a sodium resonance device. The power spectra of the observed fluctuations show that (1) the 5-minute oscillation has an horizontal coherence of 35,000 km at the level of the sodium line formation; (2) the corresponding peak at 3.3 mHz is not predominant for scales greater than 5'. New oscillations appear with a 10-minute period. Title: Transformation in solar telescope of the Nice Observatory 40 cm coude refractor Authors: Aime, C.; Demarcq, J.; Fossat, E.; Ricort, G. Bibcode: 1974NROpt...5..257A Altcode: No abstract at ADS Title: Observation of the Solar Photospheric Oscillations Using a Sodium Optical Resonance Device and an Optical Spatial Filtering Authors: Fossat, E. Bibcode: 1974A&AS...15..475F Altcode: No abstract at ADS Title: Contribution to the Observation of the Photospheric Oscillations Authors: Fossat, E.; Ricort, G. Bibcode: 1973SoPh...28..311F Altcode: Observations of the 300 s photospheric oscillation on large solar surfaces (up to 5'20″ in diameter) using a sodium optical resonance cell seem to show that the power at long horizontal wavelengths is larger than previous results would indicate. In order to get more information about the spatial distribution of the energy, a new observational method has been perfected, which will allow us to obtain the spatiotemporal power spectrum. Title: A Sodium Experiment for Photospheric Velocity Field Observations Authors: Fossat, E.; Roddier, F. Bibcode: 1971SoPh...18..204F Altcode: A method for studying small scale photospheric velocity fields with a balloon experiment is proposed. A sodium resonance cell is used with a diffraction limited telescope. Good pointing accuracy is not necessary. Preliminary results of ground-based observations are given. Title: Mesures photographiques d'étoiles doubles Authors: Fossat, Eric Bibcode: 1970A&AS....1..409F Altcode: On donne 246 mesures photographiques de 95 couples, les cliche's ayant ete' faits a' la lunette de 50 em de l'Observatoire de Nice, la plupart avec Un agrandisseur de Barlow multipliant par trois la longueur foe ale de l'instrnment, et quelques-uns au foyer direct.