Author name code: nisenson ADS astronomy entries on 2022-09-14 author:"Nisenson, Peter" ------------------------------------------------------------------------ Title: An Introduction to Optical Stellar Interferometry Authors: Labeyrie, A.; Lipson, S. G.; Nisenson, P. Bibcode: 2014iosi.book.....L Altcode: 1. Introduction; 2 Basic concepts: a qualitative introduction; 3. Interference, diffraction and coherence; 4. Aperture synthesis; 5. Optical effects of the atmosphere; 6. Single-aperture techniques; 7. Intensity interferometry; 8. Amplitude interferometry: techniques and instruments; 9. The hypertelescope; 10. Nulling and coronagraphy; 11. A sampling of interferometric science; 12. Future ground and space projects; Appendices. Title: An Introduction to Optical Stellar Interferometry Authors: Labeyrie, A.; Lipson, S. G.; Nisenson, P. Bibcode: 2006iosi.book.....L Altcode: 1. Introduction; 2 Basic concepts: a qualitative introduction; 3. Interference, diffraction and coherence; 4. Aperture synthesis; 5. Optical effects of the atmosphere; 6. Single-aperture techniques; 7. Intensity interferometry; 8. Amplitude interferometry: techniques and instruments; 9. The hypertelescope; 10. Nulling and coronagraphy; 11. A sampling of interferometric science; 12. Future ground and space projects; Appendices. Title: Precise Radial Velocities with an Upgraded Advanced Fiber Optic Echelle (AFOE) Authors: Walters, M. A.; Korzennik, S. G.; Nisenson, P.; Henry, G. W. Bibcode: 2006AAS...20721108W Altcode: The Advanced Fiber Optic Echelle (AFOE) has been used to make precise radial velocity (PRV) observations for some 12 years. The AFOE spectrograph was initially designed as a test-bed for PRV techniques for astroseismology and planet detection, and tried to provide both short term and long term stability. The resulting trade-offs between spectral resolution, range, and coverage led to a low efficiency design. In order to optimize PRVs obtained with the iodine cell technique, the spectrograph was recently upgraded, increasing the throughput and spectral coverage while reducing the maximum resolution and range. The instrument was also moved from the 60" Tillinghast telescope at the Fred Lawrence Whipple Observatory, located at Mt. Hopkins (AZ), to the 100" Hooker telescope, located at Mt. Wilson (CA). We describe the instrumental changes required for the spectrograph upgrade as well as those needed to accommodate the 100" telescope.

As a result of the instrumental changes, the data configuration has changed significantly. One would like to be able to combine radial velocities obtained before the upgrade with those obtained after, but one must take care in doing so. We describe the methodology developed to allow us to use all of the PRVs together. We also detail the precision achieved for this technique, along with the inherent precision of the upgraded configuration.

Finally, we present the radial velocities we have obtained for HD 185395 as an interesting example of our studies. This triple system shows large radial velocity variations. We compare the RV variations with observed photometric changes, and present period analyses for both data sets.

This work is funded by NASA/JPL/SIM (subcontract no. 1259554). Title: An Introduction to Astronomical Interferometry Authors: Labeyrie, Antoine; Lipson, Stephen; Nisenson, Peter Bibcode: 2006iai..book.....L Altcode: No abstract at ADS Title: Study of Coronagraphic Techniques Authors: Tolls, V.; Nisenson, P.; Aziz, M. J.; Gonsalves, R. A.; Korzennik, S. G.; Labeyrie, A.; Lyon, R. G.; Melnick, G. J.; Woodruff, R. A. Bibcode: 2004AAS...20517104T Altcode: 2005BAAS...37..376T Direct imaging of extra-solar planets is important for determining the properties of individual planets and to study multi-planet systems. Obtaining spectra of extra-solar planets enables us to constrain the composition of planetary atmospheres and surfaces, their climates, and their rotation periods. The techniques required to isolate and detect an extra-solar planet next to its host star are quite challenging and require significant improvement. SAO is setting up a testbed to study coronagraphic techniques, starting with Labeyrie's multi-step speckle reduction technique. This technique incorporates a speckle phase corrector and second occulter for speckle light suppression. The goal is to study this technique in the testbed for its application in coronagraphic cameras. In addition, the testbed will be used to characterize soft-edge occulters. Simulations of soft-edge occulters with a Gaussian absorption profile show a promising reduction of the flux in the core of the point spread function in coronagraphs. We expect this to lead to a reduction in the inner working distance and to an increase in contrast ratio compared to a Lyot coronagraph. The occulters for the tests will be developed in Harvard's Department of Engineering and Applied Sciences and by Lockheed-Martin Corp. This poster will present the setup of SAO's testbed, simulations for all developments, and first test results. Title: Calculating Velocity Shifts Between the Pre- and Post-Upgrade AFOE Data Sets Authors: Miller, J. K.; Korzennik, S. G.; Nisenson, P. Bibcode: 2003AAS...203.1710M Altcode: 2003BAAS...35.1235M We present the results of our efforts to develop a procedure to determine the velocity shifts between the pre- and post-upgrade stellar reference spectra observed with the Advanced Fiber Optic Echelle (AFOE). The AFOE spectrograph was upgraded to increase its efficiency in measuring radial velocities by rearranging the physical set-up of the optical system. While observing roughly the same wavelength range, the post-upgrade spectra have a different ratio of wavelength to pixels and gaps in the data where pieces of the spectrum were not projected onto the CCD. These differences necessitated taking new stellar references of each star system. All velocity measurements for a star are made relative to this reference. However, there is an unknown velocity shift between every pair of new and old stellar reference spectra simply because they were observed on different nights. The differences in the spectra prevent us from recalculating all of the velocities relative to one reference or the other. To overcome this problem, we have been developing a procedure that models the new stellar reference with a parameterized function of the old reference, and the velocity shift is one parameter of the model. We independently model each wavelength range of the new spectrum that overlaps the old spectrum, which gives us twelve measurements of the velocity shift. The spread in these results gives us an idea of the precision of our calculations, and our goal precision is ∼ 1 ms-1.

This work was supported in part by the SAO intern program under NSF grant AST-9731923. Title: The ELODIE survey for northern extra-solar planets. II. A Jovian planet on a long-period orbit around GJ 777 A Authors: Naef, D.; Mayor, M.; Korzennik, S. G.; Queloz, D.; Udry, S.; Nisenson, P.; Noyes, R. W.; Brown, T. M.; Beuzit, J. L.; Perrier, C.; Sivan, J. P. Bibcode: 2003A&A...410.1051N Altcode: 2003astro.ph..6586N We present radial-velocity measurements obtained with the ELODIE and AFOE spectrographs for GJ 777 A (HD 190360), a metal-rich ([Fe/H] = 0.25) nearby (d = 15.9 pc) star in a stellar binary system. A long-period low radial-velocity amplitude variation is detected revealing the presence of a Jovian planetary companion. Some of the orbital elements remain weakly constrained because of the smallness of the signal compared to our instrumental precision. The detailed orbital shape is therefore not well established. We present our best fitted orbital solution: an eccentric (e = 0.48) 10.7-year orbit. The minimum mass of the companion is 1.33 MJup.

Based on observations made with the ELODIE echelle spectrograph mounted on the 1.93-m Telescope at the Observatoire de Haute-Provence (CNRS) and with the AFOE spectrograph mounted on the 1.5-m Telescope at the Fred Lawrence Whipple Observatory (SAO).

The ELODIE and AFOE measurements discussed in this paper are only 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/410/1051 Title: Comparison of several coronagraphic approaches to the Terrestrial Planet Finder Authors: Ridgway, Stephen T.; Burrows, Christopher J.; Friedman, Edward J.; Gezari, Daniel Y.; Harwit, Martin O.; Kaplan, Michael H.; Kaylor, Larry; Lyon, Richard G.; Melnick, Gary J.; Nisenson, Peter; Peterson, Lee D.; Spergel, David N.; Woodruff, Robert A. Bibcode: 2003ESASP.539..561R Altcode: 2003toed.conf..561R Planetological and technical issues have led to a renewed interest in visible coronographic concepts for a Terrestrial Planet Finder mission. This has stimulated rapid development of new, generalized coronagraphic techniques, including exotic apodizations and nulling schemes. Hitherto, it has been difficult to compare different concepts, owing to the complex interaction between details of the concepts and instrument and mission parameters and optimization. Title: VizieR Online Data Catalog: ELODIE survey for northern extra-solar planets. II. (Naef+, 2003) Authors: Naef, D.; Mayor, M.; Korzennik, S. G.; Queloz, D.; Udry, S.; Nisenson, P.; Noyes, R. W.; Brown, T. M.; Beuzit, J. L.; Perrier, C.; Sivan, J. P. Bibcode: 2003yCat..34101051N Altcode: Here are the 69 radial-velocity measurements of GJ 777A (HD 190360) used for deriving the orbital solution of this star. These velocities were obtained using the ELODIE echelle spectrograph mounted on the 1.93-m Telescope at Observatoire de Haute-Provence (France) and the AFOE spectrograph mounted on the 1.5-m Telescope at the Fred Lawrence Whipple Observatory (USA).

(1 data file). Title: Calculation of Optimized Apodizers for a Terrestrial Planet Finder Coronagraphic Telescope Authors: Gonsalves, R.; Nisenson, P. Bibcode: 2003PASP..115..706G Altcode: 2002astro.ph.10166G One of two approaches to implementing NASA's Terrestrial Planet Finder is to build a space telescope that utilizes the techniques of coronagraphy and apodization to suppress diffraction and image exoplanets. We present a method for calculation of a telescope's apodizer that suppresses the sidelobes of the image of a star so as to optimally detect an Earth-like planet. Given the shape of a telescope's aperture and given a search region for a detector, we solve an integral equation to determine an amplitude modulation (an apodizer) that suppresses the star's energy in the focal plane search region. The method is quite general and yields as special cases the product apodizer reported by Nisenson & Papaliolios and the prolate spheroidal apodizer of Kasdin et al. and Aime et al. We show computer simulations of the apodizers and the corresponding point-spread functions for various aperture-detector configurations. Title: Motions of Isolated G-Band Bright Points in the Solar Photosphere Authors: Nisenson, P.; van Ballegooijen, A. A.; de Wijn, A. G.; Sütterlin, P. Bibcode: 2003ApJ...587..458N Altcode: 2002astro.ph.12306N Magnetic elements on the quiet Sun are buffeted by convective flows that cause lateral motions on timescales of minutes. The magnetic elements can be observed as bright points (BPs) in the G band at 4305 Å. We present observations of BPs based on a long sequence of G-band images recorded with the Dutch Open Telescope and postprocessed using speckle-masking techniques. From these images we measured the proper motions of isolated BPs and derived the autocorrelation function of their velocity relative to the solar granulation pattern. The accuracy of BP position measurements is estimated to be less than 23 km on the Sun. The rms velocity of BPs (corrected for measurement errors) is about 0.89 km s-1, and the correlation time of BP motions is about 60 s. This rms velocity is about 3 times the velocity measured using cork tracking, almost certainly due to the fact that isolated BPs move more rapidly than clusters of BPs. We also searched for evidence of vorticity in the motions of G-band BPs. Title: ExPO: a Discovery-class apodized square aperture exo-planet imaging space telescope concept Authors: Gezari, Daniel Y.; Nisenson, Peter; Papaliolios, Costas D.; Melnick, Gary J.; Lyon, Richard G.; Harwit, Martin; Ridgway, Stephen T.; Woodruff, Robert A. Bibcode: 2003SPIE.4860..302G Altcode: The Extrasolar Planet Observatory (ExPO) is envisioned as a Discovery-class space telescope for the direct detection and characterization of extra-solar planets. ExPO would also demonstrate the feasibility of a number of technologies which could be critical to the ultimate success of the Terrestrial Planet Finder mission. ExPO would detect a wide range of planet types in the visible and near IR, and do spectrophotometry and spectroscopy on many of the detected objects. The apoodized square aperture coronagraphic space telescope is designed to resolve faint companions near much brighter point-like sources by achieving very high dynamic range imaging at separations as small as 0.1 arcsec. Title: Extra-solar planetary imager (ESPI) for space-based Jovian planetary detection Authors: Lyon, Richard G.; Gezari, Daniel Y.; Melnick, Gary J.; Nisenson, Peter; Papaliolios, Costas D.; Ridgway, Stephen T.; Friedman, Edward J.; Harwit, Martin; Graf, Paul Bibcode: 2003SPIE.4860...45L Altcode: The Extra-Solar Planetary Imager (ESPI) is envisioned as a space based, high dynamic range, visible imager capable of detecting Jovian like planets. Initially proposed as a NASA Midex (NASA/Medium Class Explorer) mission (PI:Gary Melnick), as a space-based 1.5 x 1.5 m2 Jacquinot apodized square aperture telescope. The combination of apodization and a square aperture telescope reduces the diffracted light from a bright central source increasing the planetary to stellar contrast over much of the telescope focal plane. As a result, observations of very faint astronomical objects next to bright sources with angular separations as small as 0.32 arcseconds become possible. This permits a sensitive search for exo-planets in reflected light. ESPI is capable of detecting a Jupiter-like planet in a relatively long-period orbit around as many as 160 to 175 stars with a signal-to-noise ratio > 5 in observations lasting maximally 100 hours per star out to ~16 parsecs. We discuss the scientific ramifications, an overview of the system design including apodizing a square aperture, signal to noise issues and the effect of wavefront errors and the scalability of ESPI with respect to NASA's Terrestrial Planet Finder mission. Title: The Extrasolar Planet Imager (ESPI) Authors: Nisenson, P.; Melnick, G. J.; Geary, J.; Holman, M.; Korzennik, S. G.; Noyes, R. W.; Papaliolios, C.; Sasselov, D. D.; Fischer, D.; Gezari, D.; Lyon, R. G.; Gonsalves, R.; Hardesty, C.; Harwit, M.; Marley, M. S.; Neufeld, D. A.; Ridgway, S. T. Bibcode: 2003ASPC..294..633N Altcode: 2002astro.ph.10046N ESPI has been proposed for direct imaging and spectral analysis of giant planets orbiting solar-type stars. ESPI extends the concept suggested by Nisenson and Papaliolios (2001) for a square aperture apodized telescope that has sufficient dynamic range to directly detect extrasolar planets. With a 1.5-meter square mirror, ESPI can deliver high dynamic range imagery as close as 0.3 arcseconds to bright sources, permitting a sensitive search for extrasolar planets around nearby stars and a study of their characteristics in reflected light. Title: High-Resolution Imaging of the Solar Photosphere Using Simultaneous G-Band and Continuum Observations Authors: van Ballegooijen, A. A.; Nisenson, P. Bibcode: 2002AAS...200.3801V Altcode: 2002BAAS...34..698V Imaging of the Sun with ground-based telescopes requires accurate correction for the effects of turbulence in the Earth's atmosphere (``seeing"). An observed solar image is a convolution of a true solar image with a point spread function (PSF) describing the seeing effects. We present a new method for image reconstruction that uses pairs of images taken at two nearby wavelengths (G-band, 430.5 nm, and nearby continuum, 450.8 nm). Each image pair is taken strictly simultaneously, so that the two images are affected by the same PSF. A burst of 21 such image pairs is taken within a few seconds; the sun does not change much during this time, but the seeing varies randomly from one pair to the next. We determine the true solar images (and 21 PSFs) by iterative deconvolution. The method is applied to measurements obtained at the Dunn Solar Telescope (NSO/Sacramento Peak) on November 2, 2001. Preliminary results from the analysis of these data are presented. This work is supported by a grant from the National Science Foundation. Title: The Extra-Solar Planet Imager (ESPI): A Proposed MIDEX Mission Authors: Melnick, G. J.; Fischer, D.; Geary, J. C.; Gezari, D. Y.; Hardesty, C.; Harwit, M.; Holman, M.; Korzennik, S. G.; Lyon, R. G.; Marley, M. S.; McElroy, M. B.; Neufeld, D. A.; Nisenson, P.; Noyes, R. W.; Papaliolios, C.; Ridgway, S. T.; Sasselov, D. D. Bibcode: 2001AAS...199.0910M Altcode: 2002BAAS...34..559M ESPI is a project that has been proposed as a NASA MIDEX for direct imaging and spectral analysis of giant planets orbiting solar-type stars. ESPI extends the concept suggested by Nisenson and Papaliolios (2001) for a square aperture apodized telescope that has sufficient dynamic range to directly detect exo-planets. ESPI can deliver high dynamic range imagery as close as 0.32 arcseconds to bright sources, permitting a sensitive search for exoplanets around nearby stars and a study of their characteristics in reflected light. It also permits unique observations of many Galactic, extragalactic and cosmological sources. The ESPI Survey will be conducted with a square 1.5 x 1.5-meter telescope mirror, operated in conjunction with a Jacquinot apodization mask that has a throughput of more than 30 percent. The system is capable of detecting Jupiter-like planets in relatively long-period orbits around as many as 160 to 175 stars with a signal-to-noise ratio greater than 5. In addition to the survey, ESPI will also study a few of the brightest discovered planets spectroscopically and spectrophotometrically to distinguish ice giants like Uranus and Neptune from gas giants like Jupiter and Saturn, and to determine whether super-Earth and super-Venus planets exist. Nisenson, P. and Papaliolios, C. 2001, ApJ, 548, L 201. Title: Analysis of High Contrast Imaging Techniques for Space Based Direct Planetary Imaging Authors: Lyon, R. G.; Gezari, D. Y.; Nisenson, P. Bibcode: 2001AAS...198.7709L Altcode: 2001BAAS...33..903L The recent numerous detections of Jupiter and Saturn like planets in has driven a resurgence in research of space based high contrast imaging techniques for direct planetary imaging. Work is currently ongoing for concepts for NASA's Terrestrial Planet Finder mission and a number of study teams have been funded. The authors are members of one team. We report on our ongoing investigations of a number of techniques for direct detection and imaging of Earth-like planets around nearby stellar sources. Herein, we give a quantitative analysis of these techniques and compare and contrast them via computer simulations. The techniques we will be reporting on are Bracewell Interferometry, Nisenson Apodized Square Aperture, and Coronagraphic masking techniques. We parameterize our results with respect to wavelength, aperture size, effects of mirror speckle, both mid- and high-spatial frequency, detector and photon noise as well pointing error. Title: Detection of Earth-like Planets Using Apodized Telescopes Authors: Nisenson, Peter; Papaliolios, Costas Bibcode: 2001ApJ...548L.201N Altcode: 2001astro.ph..1241N The mission of NASA's Terrestrial Planet Finder (TPF) is to find Earth-like planets orbiting other stars and characterize the atmospheres of these planets using spectroscopy. Because of the enormous brightness ratio between the star and the reflected light from the planet, techniques must be found to reduce the brightness of the star. The current favorite approach to doing this is with interferometry: interfering the light from two or more separated telescopes with a π phase shift, nulling out the starlight. While this technique can, in principle, achieve the required dynamic range, building a space interferometer that has the necessary characteristics poses immense technical difficulties. In this paper, we suggest a much simpler approach to achieving the required dynamic range. By simply adjusting the transmissive shape of a telescope aperture, the intensity in large regions around the stellar image can be reduced nearly to zero. This approach could lead to construction of a TPF using conventional technologies, requiring space optics on a much smaller scale than the current TPF approach. Title: A New Technique for Terrestrial Planet Finding Authors: Nisenson, P.; Papaliolios, C. Bibcode: 2000AAS...197.4909N Altcode: 2000BAAS...32Q1486N The mission of NASA's Terrestrial Planet Finder (TPF) is to find Earth-like planets orbiting other stars and characterize the atmospheres of these planets using spectroscopy. Because of the enormous brightness ratio between the star and the reflected light from the planet, techniques must be found to reduce the brightness of the star. The current favorite approach to doing this is with infrared interferometry: interfering the light from two (or more) separated telescopes with a pi/2 phase shift, nulling out the starlight and allowing detection of the reflected light from the planet. While this technique can, in principle, achieve the required dynamic range, building a space interferometer that has the necessary characteristics poses immense technical difficulties. In this paper, we suggest a much simpler approach to achieving the required dynamic range. This approach could lead to construction of a TPF that uses conventional technology and operates in the visible, requiring space optics on a much smaller scale than the current TPF approach. We wish to acknowledge support for this work from an SVS subcontract (SVS Inc SUB-00-095) for TPF studies to the Smithsonian Astrophysical Observatory. Title: Temperature, density and magnetic field structure of the corona during the total eclipse of 1999 August 11 Authors: Habbal, S. R.; Johnson, J.; Nisenson, P.; Woo, R.; Fineschi, S.; Esser, R.; Wood, C. H.; Hale, J.; Forman, M. A.; Johnson, J. A.; Jabbour, J. Bibcode: 2000SPD....31.0235H Altcode: 2000BAAS...32..817H The goal of the eclipse expedition of the Harvard-Smithsonian Center for Astrophysics on 1999 August 11 to Ayn Diwar in Syria was to explore the temperature, density and magnetic structure of the corona through simultaneous imaging in the Fe X 6374, XIV 5303 and XI 7892 Angstroms lines, the Hα 6563 Angstroms line, and the polarized brightness or white light. Polarization measurements were made in the Fe XIV 5303 Angstroms and Hα 6563 Angstroms lines to yield the direction of the coronal magnetic field. Inferences of the temperature distribution were made from the three iron lines, while density profiles were derived from the polarized brightness measurements. Supporting space based observations were acquired with LASCO and UVCS on SOHO. The comprehensive diagnostic resulting from the analysis of the observations of the close-to-spherically symmetric corona of 1999 August 11 approaching solar maximum will be presented. Funding for this research was provided by NSF grant ATM 9521733 to the Smithsonian Astrophysical Observatory. We acknowledge the generous hospitality and support bestowed upon the team by the Syrian Ministry of Higher Education to conduct the experiment in Syria. The digitization of the photographic film was made with the help of Dr. J. Thornton and S. Sarafian from the Image Science Laboratory at Polaroid Corporation. Title: A High-Eccentricity Low-Mass Companion to HD 89744 Authors: Korzennik, Sylvain G.; Brown, Timothy M.; Fischer, Debra A.; Nisenson, Peter; Noyes, Robert W. Bibcode: 2000ApJ...533L.147K Altcode: 2000astro.ph..3045K HD 89744 is an F7 V star with a mass of 1.4 Msolar, an effective temperature of 6166 K, an age of 2.0 Gyr, and metallicity [Fe/H]=0.18. The radial velocity of the star has been monitored with the Advanced Fiber-Optic Echelle spectrograph at the Whipple Observatory since 1996, and evidence has been found for a low-mass companion. The data were complemented by additional data from the Hamilton spectrograph at Lick Observatory during the companion's periastron passage in the fall of 1999. As a result, we have determined the star's orbital wobble to have a period P=256 days, an orbital amplitude K=257 m s-1, and an eccentricity e=0.7. From the stellar mass, we infer that the companion has a minimum mass m2sini=7.2 MJ in an orbit with a semimajor axis a2=0.88 AU. The eccentricity of the orbit, among the highest known for extrasolar planets, continues the trend that extrasolar planets with semimajor axes greater than about 0.15 AU tend to have much higher eccentricities than are found in our solar system. The high metallicity of the parent star reinforces the trend that parent stars of extrasolar planets tend to have high metallicity. Title: Evidence for Multiple Companions to υ Andromedae Authors: Butler, R. Paul; Marcy, Geoffrey W.; Fischer, Debra A.; Brown, Timothy M.; Contos, Adam R.; Korzennik, Sylvain G.; Nisenson, Peter; Noyes, Robert W. Bibcode: 1999ApJ...526..916B Altcode: The bright F8 V star υ Andromedae was previously reported to have a 4.6 day Doppler velocity periodicity, consistent with having a Jupiter-mass companion orbiting at 0.059 AU. Follow-up observations by both the Lick and Advanced Fiber-Optic Echelle spectrometer (AFOE) planet survey programs confirm this periodicity and reveal additional periodicities at 241 and 1267 days. These periodicities are consistent with Keplerian orbital motion and imply two additional companions orbiting at 0.83 and 2.5 AU, with minimum (Msini) masses of 2.0 and 4.6 MJUP, respectively. Non-Keplerian explanations for the observed Doppler velocity variations, including radial and nonradial pulsations, rotational modulation of surface features, and stellar magnetic cycles, are examined. These explanations seem unlikely based on the observed photometric and chromospheric stability of the star. This putative three-planet system is found to be dynamically stable by both analytic techniques and numerical simulations. The outer two companions both reside in eccentric orbits, as do all nine known extrasolar planet candidates in distant orbits. If real, this multiple-planet system is the first around a main-sequence star, and its study should offer insights into planet formation, planet-planet interactions, and the observed eccentricities of planetary orbits.

Based on observations obtained at Lick Observatory, operated by the University of California, and at the Whipple Observatory, operated by the Smithsonian Astrophysical Observatory. Title: Evidence for a system of planets orbiting Upsilon Andromedae. Authors: Noyes, R. W.; Korzennik, S. G.; Nisenson, P.; Holman, M. J.; Contos, A.; Brown, T. M. Bibcode: 1999BAAS...31.1236N Altcode: No abstract at ADS Title: An Upper Limit on the Reflected Light from the Planet Orbiting the Star τ Bootis Authors: Charbonneau, David; Noyes, Robert W.; Korzennik, Sylvain G.; Nisenson, Peter; Jha, Saurabh; Vogt, Steven S.; Kibrick, Robert I. Bibcode: 1999ApJ...522L.145C Altcode: 1999astro.ph..7195C The planet orbiting τ Boo at a separation of 0.046 AU could produce a reflected light flux as bright as 1×10-4 relative to that of the star. A spectrum of the system will contain a reflected light component which varies in amplitude and Doppler shift as the planet orbits the star. Assuming the secondary spectrum is primarily the reflected stellar spectrum, we can limit the relative reflected light flux to be less than 5×10-5. This implies an upper limit of 0.3 for the planetary geometric albedo near 480 nm, assuming a planetary radius of 1.2 RJup. This albedo is significantly less than that of any of the giant planets of the solar system and is not consistent with certain published theoretical predictions. Title: Evidence for a System of Planets Orbiting Upsilon Andromedae Authors: Noyes, R. W.; Korzennik, S. G.; Nisenson, P.; Holman, M. J.; Contos, A.; Brown, T. M. Bibcode: 1999AAS...194.1404N Altcode: 1999BAAS...31..847N Using the Advanced Fiber Optic Echelle (AFOE) spectrograph at SAO's Whipple Observatory, we have monitored the radial velocity of Upsilon Andromedae since September 1994. Similar observations were made by the "Lick" group (P. Butler, G. Marcy, D. Fischer; see Paper 14.02).The AFOE data show, in addition to the already known close-in ``hot Jupiter'' in a 4.6-day circular orbit, two additional companions. The middle companion has a well-defined orbit, with semi-major axis about 0.83 AU, period 243.5 days, eccentricity 0.22, and minimum mass (M sin i) of 2 Jupiter masses. This is in very close agreement with independent findings by the Lick group. The AFOE data alone do not yield well-determined orbital parameters for the outer companion, because the total observing span encompasses only about one period of its orbit. However, the data are consistent with parameters derived for that companion by the Lick group from data with a longer time span, and when combined with the Lick data yield a semi-major axis of 2.5 AU, orbital period of 1267 days, eccentricity of 0.41, and minimum mass about 4.6 Jupiter masses. These results, independently obtained by two different groups with different instruments and analysis methodologies, together give strong indications that a true planetary ``system'' has now been discovered around a star like our own. We have carried out numerical integrations which show that this system can be stable, but only for certain combinations of periods, masses, and eccentricities of the outer two companions. The stability requirement thus provides a prediction that can be tested as the orbital elements of the outer companion are refined. In addition, it imposes an upper limit on the actual planetary masses, and on the difference in orbital inclination of the two outer planets. Finally, the numerical integrations imply that the longitudes of periastron of the two outer companions are locked to nearly the same value, in accord with the present observations. This work was supported by NASA, NSF, and the Smithsonian Institution. Title: A Second Bright Source Detected near SN 1987A Authors: Nisenson, Peter; Papaliolios, Costas Bibcode: 1999ApJ...518L..29N Altcode: 1999astro.ph..4109N Speckle interferometry observations, made just 30 and 38 days after the explosion of SN 1987A (which was first seen in 1987 February 23), showed evidence of a bright source separated from the SN by only 60 mas. The reprocessing of that data, using new image reconstruction algorithms, has resulted in much cleaner images that not only clearly show the bright spot reported in 1987 but also show a second spot on the opposite side of the SN with a larger spatial separation. If the spots were ejected from the SN, then the velocities of the spots are relativistic; the second spot appears to be superluminal and must be blueshifted. We explore the consequences of these results on the geometry of the SN 1987A system, and we conclude that our observations may well be evidence of relativistic jets emanating from the supernova. Title: VizieR Online Data Catalog: Double star measurements 1995-1997 (Aristidi+ 1999) Authors: Aristidi, E.; Prieur, J. -L.; Scardia, M.; Koechlin, L.; Avila, R.; Carbillet, M.; Lopez, B.; Rabbia, Y.; Nisenson, P.; Gezari, D. Bibcode: 1999yCat..41340545A Altcode: We present speckle observations of 48 double and multiple stars observed with the 2-meter ``Telescope Bernard Lyot'' (TBL) in December 1995, January 1997 and June 1997. Angular separations, absolute position angles and relative photometry result from these observations. New orbital elements have been recalculated for 8 double stars. (2 data files). Title: Speckle observations of double and multiple stars at PIC du Midi: Measurements during 1995 and 1997 and new orbits Authors: Aristidi, É.; Prieur, J. -L.; Scardia, M.; Koechlin, L.; Avila, R.; Carbillet, M.; Lopez, B.; Rabbia, Y.; Nisenson, P.; Gezari, D. Bibcode: 1999A&AS..134..545A Altcode: We present speckle observations of 48 double and multiple stars observed with the 2-meter ``Télescope Bernard Lyot'' (TBL) in December 1995, January 1997 and June 1997. Angular separations, absolute position angles and relative photometry result from these observations. New orbital elements have been recalculated for 8 double stars. Based on observations made with 2 m Telescope Bernard Lyot, Pic du Midi, France. Tables 3 to 10 are only available in electronic form only via the CDS at ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/Abstract.html. Figures 3 and 4 are only available in electronic form via http://edpsciences.com Title: Doppler Imaging of Stellar Oscillations: Multi-Site Observations of Epsilon Cephei Authors: Kennelly, E. J.; Brown, T. M.; Ehrenfreund, P.; Foing, B.; Hao, J.; Horner, S.; Korzennik, S.; Nisenson, P.; Noyes, R.; Sonnentrucker, P. Bibcode: 1999ASPC..185..264K Altcode: 1999IAUCo.170..264K; 1999psrv.conf..264K We investigate the oscillation properties of ɛ Cep using a series of specialized techniques designed to extract and analyze time variations in absorption line profiles. To obtain the necessary temporal coverage for this investigation, multi-site observations were collected at 3 sites (China, France, Arizona) all equipped with high-resolution echelle spectrographs. From these observations, we find evidence for a very rich spectrum of modes in ɛ Cep. Title: Dynamics of Magnetic Elements in the Photosphere and the Formation of Spicules Authors: van Ballegooijen, A. A.; Nisenson, P. Bibcode: 1999ASPC..183...30V Altcode: 1999hrsp.conf...30V We consider the proper motions of photospheric magnetic elements, and the effects of these motions on flows at larger heights. We summarize the results from recent analyses of high resolution G-band data obtained at the Swedish Vacuum Solar Telescope (SVST) on La Palma. The G-band images show small bright features which are known to correspond to kilogauss magnetic fields. We measure the motions of these bright points and find that the autocorrelation time of the bright point velocity is about 100 s. From the observed continuum intensity images, we derive a model of the granulation flow velocity as function of time and position on the Sun. We use this flow model to simulate the horizontal motions of photospheric magnetic elements, assuming that the elements are passively advected by the granulation flow. We find that this passive advection model is in reasonable agreement with the observed spatial distribution of the G-band bright points. Finally, we use potential-field modeling to extrapolate the magnetic and velocity fields from the photosphere, where the flux tubes are well separated, to a height of 1500 km in the chromosphere, where the flux tubes fill the available volume due to the spreading out of the field lines. We find that strong shear flows occur near separatrix surfaces where neighboring flux tubes slide past each other in the chromosphere. We propose that spicules are formed in these separatrix layers. Title: The Advanced Fiber-Optic Echelle (AFOE) and Extra-Solar Planet Searches Authors: Nisenson, P.; Contos, A.; Korzennik, S.; Noyes, R.; Brown, T. Bibcode: 1999ASPC..185..143N Altcode: 1999IAUCo.170..143N; 1999psrv.conf..143N The Advanced Fiber-Optic Echelle (AFOE) is a fiber-fed bench-top spectrograph specifically designed for precise radial velocity observations. The AFOE is permanently located at the 1.5-m telescope at Smithsonian's Whipple Observatory in Arizona and is regularly used for monitoring exo-planet candidate stars and for asteroseismology observations. In this paper, we discuss the status of the instrument, as well as an upgrade to the instrument, a Fabry-Perot reference, which may prove important both for the AFOE and for all precise radial velocity (PRV) facilities. Title: The Planet Orbiting ρ Coronae Borealis Authors: Noyes, R. W.; Contos, A. R.; Korzennik, S. G.; Nisenson, P.; Brown, T. M.; Horner, S. D. Bibcode: 1999ASPC..185..162N Altcode: 1999IAUCo.170..162N; 1999psrv.conf..162N Continuing precise radial velocity observations of ρ Coronae Borealis have allowed the determination of updated parameters of the 40-day orbit of its Jupiter-mass companion. This confirms the near-zero eccentricity of the orbit, and provides improved predictions for the times of possible transit of the companion in front of the star. The new data provide more stringent upper limits to the mass of a possible second companion to the system. The orbital parameters are discussed in the light of several different scenarios for the origin and migration of extra-solar giant planets. Title: Dynamics of Magnetic Flux Elements in the Solar Photosphere Authors: van Ballegooijen, A. A.; Nisenson, P.; Noyes, R. W.; Löfdahl, M. G.; Stein, R. F.; Nordlund, Å.; Krishnakumar, V. Bibcode: 1998ApJ...509..435V Altcode: 1998astro.ph..2359V The interaction of magnetic fields and convection is investigated in the context of the coronal heating problem. We study the motions of photospheric magnetic elements using a time series of high-resolution G-band and continuum filtergrams obtained at the Swedish Vacuum Solar Telescope at La Palma. The G-band images show bright points arranged in linear structures (``filigree'') located in the lanes between neighboring granule cells. We measure the motions of these bright points using an object tracking technique, and we determine the autocorrelation function describing the temporal variation of the bright point velocity. The correlation time of the velocity is about 100 s. To understand the processes that determine the spatial distribution of the bright points, we perform simulations of horizontal motions of magnetic flux elements in response to solar granulation flows. Models of the granulation flow are derived from the observed granulation intensity images using a simple two-dimensional model that includes both inertia and horizontal temperature gradients; the magnetic flux elements are assumed to be passively advected by this granulation flow. The results suggest that this passive advection model is in reasonable agreement with the observations, indicating that on a timescale of 1 hr the flux tubes are not strongly affected by their anchoring at large depth. Finally, we use potential-field modeling to extrapolate the magnetic and velocity fields to larger height. We find that the velocity in the chromosphere can be locally enhanced at the separatrix surfaces between neighboring flux tubes. The predicted velocities are several km s-1, significantly larger than those of the photospheric flux tubes. The implications of these results for coronal heating are discussed. Title: Exoplanets or Dynamic Atmospheres? The Radial Velocity and Line Shape Variations of 51 Pegasi and τ Bootis Authors: Brown, Timothy M.; Kotak, Rubina; Horner, Scott D.; J. Kennelly, Edward; Korzennik, Sylvain; Nisenson, P.; Noyes, Robert W. Bibcode: 1998ApJS..117..563B Altcode: 1998astro.ph..1166B The stars 51 Pegasi and τ Bootis show radial velocity variations that have been interpreted as resulting from companions with roughly Jovian mass and orbital periods of a few days. Gray and Gray & Hatzes reported that the radial velocity signal of 51 Peg is synchronous with variations in the shape of the line λ6253 Fe I; thus, they argue that the velocity signal arises not from a companion of planetary mass but from dynamic processes in the atmosphere of the star, possibly nonradial pulsations. Here we seek confirming evidence for line shape or strength variations in both 51 Peg and τ Boo, using R = 50,000 observations taken with the Advanced Fiber Optic Echelle. Because of our relatively low spectral resolution, we compare our observations with Gray's line bisector data by fitting observed line profiles to an expansion in terms of orthogonal (Hermite) functions. To obtain an accurate comparison, we model the emergent line profiles from rotating and pulsating stars, taking the instrumental point-spread function into account. We describe this modeling process in detail. We find no evidence for line profile or strength variations at the radial velocity period in either 51 Peg or in τ Boo. For 51 Peg, our upper limit for line shape variations with 4.23 day periodicity is small enough to exclude with 10 σ confidence the bisector curvature signal reported by Gray & Hatzes; the bisector span and relative line depth signals reported by Gray are also not seen, but in this case with marginal (2 σ) confidence. We cannot, however, exclude pulsations as the source of 51 Peg's radial velocity variation because our models imply that line shape variations associated with pulsations should be much smaller than those computed by Gray & Hatzes; these smaller signals are below the detection limits both for Gray & Hatzes's data and for our own. τ Boo's large radial velocity amplitude and v sin i make it easier to test for pulsations in this star. Again we find no evidence for periodic line shape changes, at a level that rules out pulsations as the source of the radial velocity variability. We conclude that the planet hypothesis remains the most likely explanation for the existing data. Title: Study of Magnetic Structure in the Solar Photosphere and Chromosphere Authors: Noyes, Robert W.; Avrett, Eugene; Nisenson, Peter; Uitenbroek, Han; van Ballegooijen, Adriaan Bibcode: 1998nasa.reptV....N Altcode: This grant funded an observational and theoretical program to study the structure and dynamics of the solar photosphere and low chromosphere, and the spectral signatures that result. The overall goal is to learn about mechanisms that cause heating of the overlying atmosphere, and produce variability of solar emission in spectral regions important for astrophysics and space physics. The program exploited two new ground-based observational capabilities: one using the Swedish Solar Telescope on La Palma for very high angular resolution observations of the photospheric intensity field (granulation) and proxies of the magnetic field (G-band images); and the other using the Near Infrared Magnetograph at the McMath-Pierce Solar Facility to map the spatial variation and dynamic behavior of the solar temperature minimum region using infrared CO lines. We have interpreted these data using a variety of theoretical and modelling approaches, some developed especially for this project. Previous annual reports cover the work done up to 31 May 1997. This final report summarizes our work for the entire period, including the period of no-cost extension from 1 June 1997 through September 30 1997. In Section 2 we discuss observations and modelling of the photospheric flowfields and their consequences for heating of the overlying atmosphere, and in Section 3 we discuss imaging spectroscopy of the CO lines at 4.67 mu. Title: The Oscillations of Tau Pegasi Authors: Kennelly, E. J.; Brown, T. M.; Kotak, R.; Sigut, T. A. A.; Horner, S. D.; Korzennik, S. G.; Nisenson, P.; Noyes, R. W.; Walker, A.; Yang, S. Bibcode: 1998ApJ...495..440K Altcode: We present extensive spectroscopic time series observations of the multiperiodic, rapidly rotating, δ Scuti star τ Pegasi. Information about the oscillations is contained within the patterns of line-profile variation of the star's blended absorption-line spectrum. We introduce the new technique of Doppler deconvolution with which to extract these patterns by modeling the intrinsic stellar spectrum and the broadening functions for each spectrum in the time series. Frequencies and modes of oscillation are identified from the variations using the technique of Fourier-Doppler imaging and a two-dimensional least-squares cleaning algorithm. We find a rich mode spectrum with degrees up to l = 20 and with frequencies below about 35 cycles day-1. Those modes with the largest amplitudes have frequencies that lie within a narrow band. We conclude that the observed spectrum can be explained if the modes of τ Peg propagate in the prograde direction with l ~= |m| and with frequencies that are about equal in the corotating frame of the star. We discuss the implications of these results for the prospect of δ Scuti seismology. Title: A Search for Line Shape and Depth Variations in 51 Pegasi and τ Bootis Authors: Brown, Timothy M.; Kotak, Rubina; Horner, Scott D.; Kennelly, Edward J.; Korzennik, Sylvain; Nisenson, P.; Noyes, Robert W. Bibcode: 1998ApJ...494L..85B Altcode: 1997astro.ph.12279B Spectroscopic observations of 51 Pegasi and τ Bootis show no periodic changes in the shapes of their line profiles; these results for 51 Peg are in significant conflict with those reported by Gray & Hatzes. Our detection limits are small enough to rule out nonradial pulsations as the cause of the variability in τ Boo, but not in 51 Peg. The absence of line shape changes is consistent with these stars' radial velocity variability arising from planetary mass companions. Title: Exoplanet Research with the Advanced Fiber Optic Echelle Authors: Korzennik, S. G.; Brown, T. M.; Contos, A. R.; Horner, S.; Jha, S.; Kennelly, T.; Krockenberger, M.; Nisenson, P.; Noyes, R. W. Bibcode: 1998ASPC..154.1876K Altcode: 1998csss...10.1876K The AFOE is a fiber-fed bench-top echelle spectrometer installed at the Mt. Hopkins 1.5 m telescope for research in exoplanets, asteroseismology, and other topics requiring precise radial velocity measurements. Here we describe the instrumentation, observing programs, and data reduction techniques for exoplanet research with the AFOE. We also summarize recent results of our search for and characterization of exoplanets. Further information on the AFOE can be found on the Web at http://cfa-www.harvard.edu/afoe. Title: Temperatures of Cepheids from Line-Depth Ratios Authors: Krockenberger, M.; Sasselov, D.; Noyes, R.; Korzennik, S.; Nisenson, P.; Brown, T.; Kennelly, T.; Horner, S. Bibcode: 1998ASPC..154..791K Altcode: 1998csss...10..791K We present observations of 11 Cepheids and 16 non-variable supergiants with the Advanced Fiber Optics Echelle (AFOE) spectrograph. We measure the effective temperatures of Cepheids and supergiants using spectral line depth ratios and Kurucz's model atmospheres. For the Cepheids we use the fact that the reddening is constant as a function of phase as an additional constraint. We find errors in the mean temperature as small as 10 K for the best sampled Cepheids. Our temperatures and surface brightnesses disagree with the results of the Barnes-Evans method. Title: 51 Pegasi and Tau Bootis: Planets or Pulsations? Authors: Horner, S. D.; Brown, T. M.; Kennelly, E. J.; Kotak, R.; Jha, S.; Korzennik, S. G.; Krockenberger, M.; Nisenson, P.; Noyes, R. W. Bibcode: 1998ASPC..135..206H Altcode: 1998hcsp.conf..206H It has recently been suggested (Gray 1997) that the radial velocity variations observed in the spectra of 51 Pegasi are the result of stellar pulsations as opposed to the reflex motion due to an orbital companion. The AFOE group has confirmed the radial velocity variations in 51 Pegasi and t Bootis. Here we discuss the results of a search for evidence of pulsations in the AFOE data for these two stars, as well as attempt to clear up misconceptions regarding pulsations circulated as a result of the current debate about the nature of the 51 Pegasi radial velocity variations. Title: 51 Pegasi and Tau Bootis: Planets or Pulsations? Authors: Horner, S. D.; Brown, T. M.; Kennedy, E. J.; Kotak, R.; Jha, S.; Korzennik, S. G.; Krockenberger, M.; Nisenson, P.; Noyes, R. W. Bibcode: 1998ASPC..154.1860H Altcode: 1998csss...10.1860H Using data from the AFOE and simulations of pulsating stars, we are able to rule out pulsations as the cause of the radial velocity variations seen in tau Bootis and conclude that it is unlikely that pulsations are the cause of radial velocity variations seen in 51 Pegasi. Orbital companions are still the most probable causes of the radial velocity variations observed in these systems. Title: Asteroseismology of Procyon with the AFOE Authors: Horner, S. D.; Brown, T. M.; Kennelly, E. J.; Korzennik, S.; Nisenson, P.; Noyes, R. W. Bibcode: 1997AAS...191.4310H Altcode: 1997BAAS...29R1276H The Advanced Fiber Optic Echelle (AFOE) is a bench-mounted, fiber-fed echelle spectrograph designed for precision radial velocity observations. Located at the 1.5m Tillinghast telescope at Whipple Observatory, the AFOE is used to detect exoplanets and is involved in several projects in asteroseismology, including asteroseismology of Sun-like stars. Procyon has been a prime target for asteroseismology of Sun-like stars due to its proximity and its spectral type (F5 IV-V). Theory predicts that due to its low surface gravity and inefficient surface convection, the amplitudes of its p-mode pulsation modes should be relatively large, though still less than 1 m\ s(-1) . While the velocity of individual modes is extremely small, observations of Procyon with the AFOE show excess power in the frequency range between 0.5 to 1.5 MHz. This power may be the result of p-mode oscillations on Procyon, and is consistent with previous results (Brown et al. 1991). However, mode identification is required to interpret the ramifications of the observations for the star's structure, which is the goal of asteroseismology. These single-site data are limited in frequency resolution, which may prevent clear identification of individual modes. Title: Erratum: A Planet Orbiting the Star Rho Coronae Borealis: Authors: Noyes, Robert W.; Jha, Saurabh; Korzennik, Sylvain G.; Krockenberger, Martin; Nisenson, Peter; Brown, Timothy M.; Kennelly, Edward J.; Horner, Scott D. Bibcode: 1997ApJ...487L.195N Altcode: In the Letter, ``A Planet Orbiting the Star ρ Coronae Borealis'' by Robert W. Noyes, Saurabh Jha, Sylvain G. Korzennik, Martin Krockenberger, Peter Nisenson, Timothy M. Brown, Edward J. Kennelly, and Scott D. Horner (ApJ, 483, L111 [1997]), a software error caused the sign of the reported radial velocity variations of ρ Coronae Borealis to be reversed. This error has no effect on the period, amplitude, or eccentricity of the derived orbit and thus does not affect the main conclusion of the paper. However, the longitude ω of periastron reported in Table 1 is off by 180°, and the predicted time of a possible planetary transit Ttransit is off by approximately 1/2 period. The correct values are ω = 30° +/- 74° and Ttransit = 2,450,657.88 +/- 0.54 HJD. Title: A Planet Orbiting the Star ρ Coronae Borealis Authors: Noyes, Robert W.; Jha, Saurabh; Korzennik, Sylvain G.; Krockenberger, Martin; Nisenson, Peter; Brown, Timothy M.; Kennelly, Edward J.; Horner, Scott D. Bibcode: 1997ApJ...483L.111N Altcode: 1997astro.ph..4248N We report the discovery of near-sinusoidal radial velocity variations of the G0V star ρ CrB, with period 39.6 days and amplitude 67 m s-1. These variations are consistent with the existence of an orbital companion in a circular orbit. Adopting a mass of 1.0 Msolar for the primary, the companion has minimum mass about 1.1 Jupiter masses and orbital radius about 0.23 AU. Such an orbital radius is too large for tidal circularization of an initially eccentric orbit during the lifetime of the star, and hence we suggest that the low eccentricity is primordial, as would be expected for a planet formed in a dissipative circumstellar disk. Title: A Radial Velocity Search for p-Mode Pulsations in η Bootis Authors: Brown, Timothy M.; Kennelly, Edward J.; Korzennik, Sylvain G.; Nisenson, Peter; Noyes, Robert W.; Horner, Scott D. Bibcode: 1997ApJ...475..322B Altcode: The subgiant η Boo (G5 IV) has been reported to show p-mode pulsations, as evidenced by variations in the equivalent width of its hydrogen Balmer lines (reported by Kjeldsen et al.). In an attempt to confirm this report, we observed η Boo's radial velocity with the AFOE spectrograph for a total of 22 hours spread over seven successive nights in 1995 March. We find no evidence for the presence of excess power at the frequencies reported by Kjeldsen et al.; our upper limit corresponds to typical mode amplitudes of 0.5 m s-1, about 3 times smaller than the velocity amplitudes they inferred. Signals with amplitudes larger than 0.5 m s-1 may be present at other frequencies within the 0-1000 μHz range, but evidence for such signals is scanty, and typical mode amplitudes greater than 1.5 m s-1 are clearly inconsistent with our observations. Title: The AFOE Program of Extra-Solar Planet Research Authors: Noyes, R.; Jha, S.; Korzennik, S.; Krockenberger, M.; Nisenson, P.; Brown, T.; Kennelly, E.; Horner, S. Bibcode: 1997ASPC..119..119N Altcode: 1997pbss.conf..119N No abstract at ADS Title: A radial velocity search for p-modes in Procyon. Authors: Brown, T. M.; Kennelly, E. J.; Noyes, R. W.; Korzennik, S. G.; Nisenson, P.; Horner, S. D.; Catala, C. Bibcode: 1996BAAS...28..917B Altcode: No abstract at ADS Title: The oscillation modes of ɛ Cep and τ Peg. Authors: Horner, S. D.; Kennelly, E. J.; Brown, T. M.; Noyes, R. W.; Korzennik, S. G.; Nisenson, P.; Yang, S.; Walker, A. R. Bibcode: 1996BAAS...28..916H Altcode: No abstract at ADS Title: The Oscillation Modes of epsilon CEP and tau Peg Authors: Horner, S. D.; Kennelly, E. J.; Brown, T. M.; Noyes, R. W.; Korzennik, S. G.; Nisenson, P.; Yang, S.; Walker, A. Bibcode: 1996AAS...188.5901H Altcode: 1996BAAS...28Q.917H Asteroseismology of delta Scuti stars offers an attractive prospect for determining the interior properties of main sequence and slightly more evolved A- and F-type stars. Here we present detailed identifications of oscillation modes in the rapidly rotating delta Scuti stars epsilon Cep and tau Peg based on extensive observations carried out at two North American sites. Using cross-correlation and Fourier techniques we analyze the line-profile variations and the variations in the line-profile moments. A solution to the mode spectrum is sought using a genetic-based search algorithm and a line profile simulation model to reproduce the observed variations. Title: Use of Temperature-Sensitive Line Ratios for Stellar Seismology Authors: Noyes, R. W.; Korzennik, S. G.; Krockenberger, M.; Nisenson, P.; Brown, T.; Kennelly, T.; Horner, S. Bibcode: 1996AAS...188.5906N Altcode: 1996BAAS...28..918N The line depths of virtually all stellar spectral lines are sensitive to small changes in stellar temperature Teff induced by pulsations, with varying degrees (and signs) depending on the mean Teff and the line ionization and excitation state. For large-amplitude pulsators, such as Cepheids, temperatures obtained from individual line pairs are sufficiently accurate and invariant to reddening to play an important role in distance measurements. For small-amplitude pulsators, this technique is inadequate. However, by combining the information from a very large number of spectral lines recorded with high spectral resolution, such as can be provided by a cross-dispersed echelle spectrograph, it should be possible to measure temperature changes to a precision considerably greater than can be obtained by comparing single pairs of lines. We explore this possibility by using a grid of synthetic stellar spectra to provide the run of temperature sensitivity as a function of wavelength throughout the spectrum, and make specific application to spectra obtained with the Advanced Fiber Optic Echelle (AFOE) spectrograph. Title: A Radial Velocity Search for p-modes in Procyon Authors: Brown, T. M.; Kennelly, E. J.; Noyes, R. W.; Korzennik, S. G.; Nisenson, P.; Horner, S. D.; Catala, C. Bibcode: 1996AAS...188.5902B Altcode: 1996BAAS...28R.917B Procyon (alpha CMi F5 IV) has long been a promising candidate for detection of solar-like p-modes. Although several authors have reported evidence for low-amplitude (<= 10) m/s pulsations in this star, none of the existing observations are conclusive. A clear detection of such pulsations would be a significant step for asteroseismology of Sun-like stars, allowing refined estimates of the star's properties and paving the way for the study of fainter stars of similar spectral type. Identification of oscillation modes in subgiants like Procyon is expected to be difficult, however, because both the amplitudes and the frequency separations of the modes are expected to be small. To address these difficulties, we organized a joint observing campaign involving the AFOE spectrograph located at the Whipple Observatory (Mt. Hopkins, AZ) and the MUSICOS spectrograph located at Pic du Midi. Both instruments are capable of providing Doppler measurements with the required precision of a few m/s, and the 7 hour longitude separation between them allows the acquisition of relatively long uninterrupted data strings. In the event, bad weather prevented more than sporadic observations from Pic du Midi. At Mt. Hopkins, however, we obtained good observations on each of 6 consecutive nights 3-8 Feb 1996, for a total of 47 h of observing time. We discuss here the interpretation of this data set in terms of possible p-mode oscillations. Title: HD 3346 Authors: Noyes, R.; Korzennik, S.; Nisenson, P.; Jha, S.; Krockenberger, M.; Brown, T.; Kennelly, T.; Rowland, C.; Horner, S. Bibcode: 1996IAUC.6316....1N Altcode: 1996IAUC.6316Q...1N R. Noyes, S. Korzennik, P. Nisenson, S. Jha, and M. Krockenberger, Smithsonian Astrophysical Observatory; T. Brown, T. Kennelly, and C. Rowland, High Altitude Observatory; and S. Horner, Pennsylvania State University, report the detection of large short- term radial-velocity variations in the K5 III star HD 3346 = HR 152. Irregularly spaced observations were made with the Advanced Fiber Optic Echelle (AFOE) spectrometer at the 1.5-m telescope of the Whipple Observatory during the last quarters of 1993, 1994, and 1995, with more intensive observations in December 1995 and February 1996. A long-period radial-velocity variation similar to that already reported by McClure et al. (1985, PASP 97, 740) is seen with amplitude of order 500 m/s and period of order 650 days. This is consistent with a companion to HD 3346 at orbital distance about 2.5 AU. If the mass of HD 3346 is 5 solar masses, then this already-reported companion would have projected mass m sin i about 60 Jupiter masses. The AFOE data reveal the presence of shorter- term radial-velocity variations superimposed on the 650-day variation. The amplitude of the variations is in the range 150-300 m/s. Near-nightly observations in December 1995 and February 1996 show the variations to be consistent with those produced by a second orbital companion. The window function of the data would allow for its period to be near 14, 18, 24, or 40 days. Such a short period would imply that the second companion's orbit would have a semimajor axis between 0.2 and 0.4 AU; the amplitude of the variation implies that (again, if HD 3346 has a mass of 5 solar masses) this second companion has m sin i about 10 Jupiter masses. Acoustic pulsations may be an alternative source of the short-term radial-velocity variations. However, the fundamental period of acoustic pulsations in giants is expected to be only a few days; the present data could be explained by acoustic pulsations only if the star has a mass much lower than suggested by standard stellar- evolution theory. Spurious signals due to rotation of starspots appear to be unlikely because of the low reported rotational velocity for HD 3346. A definitive period for the short-period radial-velocity variation may be determinable if other contemporaneous precise radial-velocity observations of this star exist or can be obtained before the star disappears behind the sun for this observing season. Title: Estimating the Cramer-Rao Bound for Astronomical Observations: Application to the Richardson-Lucy Algorithm Authors: Zaccheo, T. S.; Gonsalves, R. A.; Nisenson, P.; Ebstein, S. M. Bibcode: 1996ApJ...458..742Z Altcode: This work addresses the problem of assigning confidence intervals to restored data obtained by applying the Richardson-Lucy algorithm to astronomical observations. The proposed solution is to estimate the Cramér-Rao bound, which describes the minimum obtainable mean square error associated with a given estimate of a parameter. This paper presents a compact method for describing the bound for Richardson-Lucy estimates. It was developed based on previously described bounds for linear restoration techniques such as Wiener filter estimates. Both one- and two-dimensional examples are presented. Title: A Radial Velocity Search for p-mode Pulsations in eta Bootis Authors: Noyes, R. W.; Korzennik, S. G.; Nisenson, P.; Brown, T. M.; Kennelly, E. J.; Horner, S. D. Bibcode: 1995AAS...18710211N Altcode: 1995BAAS...27.1429N Kjeldsen et al. 1994 (Astron. J 109, 1313 ) have reported the presence of p-mode pulsations in Balmer line equivalent widths measured in the spectrum of eta Boo (G5 IV); they give accurate frequencies for 13 modes of oscillation, and estimate velocity amplitudes for these modes of typically 1.6 m/s. We report here time-series observations of the radial velocity of eta Boo obtained with the Advanced Fiber Optic Echelle (AFOE) spectrograph. In March 1995 we obtained 555 spectra of eta Boo for a total of 21.6 hours of observing time spread over 7 consecutive nights. The radial velocity time series clearly shows the night-to-night orbital motion of eta Boo; the residual velocities after removing this motion are typically 10 m/s for single spectra, a value that is roughly consistent with shot noise limits. The power spectrum of the time series shows no evidence for Kjeldsen et al.'s frequencies. With 95 % confidence, we can rule out the presence of these 13 frequencies with typical amplitudes of 0.5 m/s or more. The spectrum is consistent with pure photon noise, but also with the presence of pulsations having other frequencies (not those given by Kjeldsen et al.) and with typical amplitudes as large as about 1.5 m/s. Possible explanations for the discrepancy between the two results are (a) an incorrect conversion between the amplitudes of equivalent width and Doppler pulsations, and (b) a fluke in the noise behavior of one or both observations. Title: Determining the AFOE's Radial Velocity Precision with Solar Observations Authors: Horner, S. D.; Brown, T. M.; Kennelly, E. J.; Noyes, R. W.; Korzennik, S. G.; Nisenson, P.; Krockenberger, M. Bibcode: 1995AAS...187.7006H Altcode: 1995BAAS...27.1380H The Advanced Fiber Optic Echelle (AFOE) is an instrument designed for high precision radial velocity observations to detect extra-solar planets and study stellar structure through asteroseismology. A 320 mu m optical fiber is used to obtain solar observations during the day to determine the precision of the instrument, and to study the relationship between stellar activity and measured radial velocities. Here we present the results of our analysis of solar data to determine the short and long term radial velocity precision of the AFOE. Title: Molecular H 2 Emission in HH 47A: Hubble Space Telescope GHRS and FOC Observations Authors: Curiel, Salvador; Raymond, John C.; Wolfire, Mark; Hartigan, Patrick; Morse, Jon; Schwartz, Richard D.; Nisenson, Peter Bibcode: 1995ApJ...453..322C Altcode: We present Hubble Space Telescope ultraviolet observations of the bow shock at the end of the HH 47 stellar jet obtained with the Goddard High Resolution Spectrograph (GHRS) and the Faint Object Camera (FOC). The GHRS spectrum shows three prominent emission lines of H2 which are produced by Lyα fluorescence and one line that we cannot identify. Fluorescence from Lyman alpha generated in the bow shock and Mach disk of HH 47A can account for the observed H2 line fluxes provided that the H2 absorbs about one-third of these Lyman alpha photons. We find that our FOC image of HH 47A is made up of about 70% hydrogen two-photon continuum and about 30% fluorescent H2 emission. This image closely resembles optical [S II] and Hα images of HH 47A but differs significantly from H2 images of the region taken at near-infrared wavelengths. This is because the two-photon continuum and the Lyα photons which drive H2 fluorescence both originate in the Hα-emitting gas, and the Lyα mean free path is small.

The presence of molecular hydrogen in HH 47A is difficult to understand. If the H2 forms in a dense region between the bow shock and the Mach disk, then the emission should be significantly more blueshifted than observed. Models that excite H2 using C-shocks or magnetic precursors assume that molecular hydrogen exists in the preshock gas of HH 47A. However, this gas lies within the wake of a previous high-velocity ejection from the star and is exposed to ionizing radiation from the Gum Nebula, so we would not expect to find any H2 in this region.

Numerical calculations indicate that the UV H2 line emission may be produced by either reformed H2 molecules in the region between the bow shock and the Mach disk or from a C-shock or magnetic precursor, while the near-infrared H2 emission observed in HH 47A arises mainly from C-shock or magnetic precursor along the wings of the bow shock. We propose that the scenario that best explains the current results is one in which the HH 47A bow shock is running into a clump of molecular gas which could be either comoving with the preshock gas or nearly stationary with respect to the ambient cloud, primary on its more distant face. Title: 51 Pegasi Authors: Mayor, M.; Queloz, D.; Marcy, G.; Butler, P.; Noyes, R.; Korzennik, S.; Krockenberger, M.; Nisenson, P.; Brown, T.; Kennelly, T.; Rowland, C.; Horner, S.; Burki, G.; Burnet, M.; Kunzli, M. Bibcode: 1995IAUC.6251....1M Altcode: M. Mayor and D. Queloz, Geneva Observatory, have reported the discovery of a Jupiter-mass object in orbit around the solar-type star 51 Peg. The announcement was made in Florence on Oct. 6 at the Ninth "Cambridge" Workshop on "Cool Stars, Stellar Systems, and the Sun". The claim is based on 18 months of precise Doppler measurements made with the ELODIE spectrograph of the Observatoire de Haute-Provence. The parameters of the orbital motion are as follows: P = 4.2293 +/- 0.0011 days, e = 0 (assumed), K = 0.059 +/- 0.003 km/s, T0 = 2449797.773 +/- 0.036. The minimum mass of the companion is 0.47 +/- 0.02 Jupiter mass. Alternative explanations for the radial-velocity variation (pulsation or spot rotation) seem to be ruled out by the absence of any significant corresponding photometric variation. Following the Oct. 6 announcement, confirmation of the 4.2-day radial-velocity variation was obtained in mid-October by G. Marcy and P. Butler (San Francisco State University, University of California at Berkeley) at the Lick Observatory, as well as by a joint team from the Harvard-Smithsonian Center for Astrophysics (R. Noyes, S. Korzennik, M. Krockenberger and P. Nisenson), the High Altitude Observatory (T. Brown, T. Kennelly and C. Rowland) and Pennsylvania State University (S. Horner). G. Burki, M. Burnet and M. Kuenzli, Geneva Observatory and Lausanne University, communicate: "Intensive photometric monitoring of 51 Peg has been carried out at the European Southern Observatory. There is no evidence for eclipses in the system. The rms of the V magnitude (on 17 nights) is 0.037, two comparison stars being used. A 4.2-day photometric variability larger than 0.002 mag can be ruled out." Title: Nightly Variations of Nonradial Oscillations in the Delta Scuti Star upsilon Ursae Majoris Authors: Korzennik, S. G.; Noyes, R. W.; Brown, T.; Nisenson, P.; Horner, S. Bibcode: 1995ApJ...443L..25K Altcode: We obtained spectra of the rapidly rotating Delta Scuti star upsilon UMa with the Advanced Fiber Optic Echelle Spectrometer (AFOE) on five successive nights in 1993 April, at a cadence of one spectrum every 5 minutes over time periods averaging 4 hours on each night. Cross-correlations of the spectra with a template spectrum from a slowly rotating star of similar spectral type yielded the pattern of features propagating across the lines, averaged over all spectral lines recorded. The spacing of the features in wavelength and their speed of motion across the line profile depend on the azimuthal order m and frequency v of propagating oscillation modes. Using a Doppler imaging analysis, we computed nightly absolute value of m-v diagrams; these show several resolved modes with effective azimuthal order m ranging from about 2 up to about 11, and frequencies between 130 and 170 microHz (i.e., periods between 2.1 and 1.6 hours). We identify the observed modes as propagating prograde modes; the corresponding retrograde modes are not observed. Viewed in a frame corotating with the star with rotation speed of 116 km/s as derived from these data, modes with m approximately 7 and with m approximately 11 have approximately the same frequency (70 microHz). However, their relative amplitude changes substantially from night to night, suggesting that (1) the coherence time of the modes is not longer than about 1 day, or (2) a possible coupling between modes of similar intrinsic frequencies causes an alternating pattern of modal amplitude, or (3) beats are being observed between unresolved modes of similar wavelength and frequency. Title: Estimating the Cramer-Rao Bound for Restored Astronomical Observations Authors: Zaccheo, T. S.; Gonsalves, R. A.; Ebstein, S. M.; Nisenson, P. Bibcode: 1995ApJ...439L..43Z Altcode: This work addresses the problem of assigning confidence intervals to estimated photometry data obtained from astronomical observations. The proposed solution is to estimate the Cramer-Rao bound, which is an analytical expression that describes the minimum obtainable mean square error associated with a given estimate of a parameter. This Letter presents a compact and simple form for the bound associated with a linear estimator such as a Wiener filter estimator. A prescription for estimating the variance associated with each element in a restored object was developed using an analytical model for observed data corrupted by either Poisson or Gaussian noise. Both one- and two-dimensional examples are presented. Title: First 2.2 micron Results From the IOTA Interferometer Authors: Dyck, H. M.; Benson, J. A.; Carleton, N. P.; Coldwell, C.; Lacasse, M. G.; Nisenson, P.; Panasyuk, A.; Papaliolios, C.; Pearlman, M. R.; Reasenberg, R. D.; Traub, W. A.; Xu, A.; Predmore, C. R.; Schloerb, F. P.; Gibson, D. M. Bibcode: 1995AJ....109..378D Altcode: We present the first infrared fringe visibility measurements made with the Infrared Optical Telescope Array on Mt. Hopkins. Effective temperatures are derived for RX Boo, RS Cnc, and Beta Peg. RX Boo is the coolest small-amplitude variable giant star to have an effective temperature determination. We compare the size of its photosphere at infrared wavelengths with the sizes of its SiO and H20 radio emission regions. We also discuss initial performance parameters for the interferometer. Title: The AFOE: A Spectrograph for Precision Doppler Studies Authors: Brown, Timothy M.; Noyes, Robert W.; Nisenson, Peter; Korzennik, Sylvain G.; Horner, Scott Bibcode: 1994PASP..106.1285B Altcode: The Advanced Fiber Optic Echelle (AFOE) is a fiber-fed echelle spectrograph designed for the measurement of stellar Doppler shifts. Using a 2k x 2k CCD detector, it samples about 55% of the wavelength range between 450 nm and 700 nm (20 echelle orders) at a single shot, with spectral resolution R = 32000 to 70000 at 500 nm, depending on the slit width employed. The AFOE employs a number of devices to assure that the calibrations necessary for accurate Doppler measurements can be properly performed. The most important of these are: (1) coupling to the telescope via a double-scrambling optical fiber system; (2) continuous calibration of the wavelength scale and point-spread function by means of an atomic emission lamp entering the spectrograph via a separate fiber and/or a molecular iodine absorption cell; (3) availability of fiber-coupled sunlight for regular calibration against the solar spectrum; (4) appropriate mechanical design and active thermal control, yielding good mechanical stability. The AFOE is coupled to the Tillinghast 1.5-m telescope at the F. L. Whipple Observatory. It presently achieves S/N = 500 in the continuum near 500 nm in 60s when observing Arcturus (alpha-Boo, m_V = -0.04). This noise level sets a limit of about 0.7 ms^-1 to the Doppler precision attainable in this length of observing time. Currently, our actual frame-to-frame repeatability is worse than the photon noise limited value by about a factor of 3 for this bright star, and about 1.5 for stars with m_V = 4. Work is continuing to refine data processing methods so that the ultimate noise limit may be approached more closely, and to improve the spectrograph's relatively low efficiency. (SECTION: Astronomical Instrumentation ) Title: Current status of the IOTA interferometer Authors: Carleton, Nathaniel P.; Traub, Wesley A.; Lacasse, Marc G.; Nisenson, Peter; Pearlman, Michael R.; Reasenberg, Robert D.; Xu, Xinqi; Coldwell, Charles M.; Panasyuk, Alexander; Benson, James A.; Papaliolios, Costas; Predmore, Read; Schloerb, F. P.; Dyck, H. M.; Gibson, David M. Bibcode: 1994SPIE.2200..152C Altcode: 1994aisi.conf..152C The first two telescopes of the Infrared-Optical Telescope Array (IOTA) project are now in place and yielding data at the Smithsonian Institution's F. L. Whipple Observatory on Mt. Hopkins, near Tucson, Arizona. The IOTA collectors are 45 cm in diameter, and may be moved to various stations in an L-shaped configuration with a maximum baseline of 38 m. A third collector will be added as soon as funding permits. Each light-collector assembly consists of a siderostat feeding a stationary afocal Cassegrain telescope that produces a 10-X reduced parallel beam, which is in turn directed vertically downward by a piezo-driven active mirror that stabilizes the ultimate image position. The reduced beams enter an evacuated envelope and proceed to the corner of the array, where they are turned back along one arm for path compensation. The delay line, in one beam, consists of two parts: one dihedral reflector positioned in a slew-and-clamp mode to give the major part of the desired delay; and a second dihedral mounted on an air-bearing carriage to provide the variable delay that is needed. After delay, the beams exit from the vacuum and are directed by dichroic mirrors into the infrared beam-combination and detection system. The visible light passes on to another area, to the image-tracker detectors and the visible-light combination and detection system. The beams are combined in pupil-plane mode on beam splitters. The combined IR beams are conveyed to two cooled single-element InSb detectors. The combined visible-light beams are focussed by lenslet arrays onto multimode optical fibers that lead to the slit of a specially-designed prism spectrometer. For the visible mode, the delay line is run at several wavelengths on one side of the zero- path point, so that several cycles of interference occur across the spectrum. First results were obtained with the IR system, giving visibilities for several K and M stars, using 2.2 micrometers radiation on a N-S baseline of 21.2 m. From these measurements we obtained preliminary estimates of effective stellar diameters in the K band. Title: High Resolution Measurements from HST Power Spectra Authors: Nisenson, P.; Falco, E.; Gonsalves, R.; Ebstein, S. Bibcode: 1994rhis.conf..337N Altcode: No abstract at ADS Title: Cramér-Rao Bound - Accuracy of HST Image Restoration Authors: Gonsalves, R. A.; Zaccheo, T. S.; Ebstein, S. M.; Nisenson, P. Bibcode: 1994rhis.conf..343G Altcode: No abstract at ADS Title: Power Spectral Analysis of HST Gravitational Lens Images Authors: Nisenson, P.; Falco, E. Bibcode: 1993AAS...183.7208N Altcode: 1993BAAS...25.1403N Gravitationally lensed QSO's have become important astronomical tools for a wide range of astrophysical problems. They provide tests of General Relativity and act as probes of intergalactic matter. They may allow direct estimates of the Hubble constant from time delay measurements and could be used to estimate dark matter in galactic halos. HST (PC) images of gravitational lens systems should provide improved measurement of positions and fluxes of the QSO images, and may allow detection and possible characterization of the lensing galaxies. However, the HST point spread function makes accurate parameter extraction more difficult. We have found that measurements made from the power spectra of these relatively simple objects provides improved accuracy and, in some cases, the discovery of features not obvious in the raw (or deconvolved) images. Title: Cramer-Rao Bound on Object Estimation from HST Imagery Authors: Gonsalves, Robert A.; Zaccheo, Scott; Ebstein, Steven M.; Nisenson, P. Bibcode: 1993AAS...18311302G Altcode: 1993BAAS...25.1459G When creating an enhanced image or estimating an object's parameters, it is important to establish the error associated with the processing. The Cramer-Rao bound is a tool to calculate the error. It gives the minimum variance that can be achieved by any estimation technique; when the technique is maximum likelihood, the estimator asymptotically approaches the bound, as the number of observations becomes large. We calculate the bound for HST WF/PC imagery and show how it can be used as an adjoint to any enhancement or estimation algorithm. The bound is sensitive to the accuracy of the point-spread function (PSF). We show results for an improved estimation of the PSF. Title: Nightly Variations of Non-Radial Oscillations in the Delta Scuti Star upsilon UMa Authors: Korzennik, S.; Noyes, R.; Brown, T.; Nisenson, P.; Horner, S. Bibcode: 1993AAS...183.8405K Altcode: 1993BAAS...25.1423K We observed the rapidly rotating Delta Scuti star upsilon UMa with the Advanced Fiber Optic Echelle (AFOE) spectrometer at the Mt. Hopkins 1.5-m telescope on 5 successive nights in April 1993. Spectra covering a total of 730 Angstroms were obtained at a 5-min cadence over about 4 hours on each night. The rotationally-broadened profiles of unblended strong lines clearly show previously-seen ``bumps" propagating from the blue side to the red side of the lines. We isolated moving features for each individual spectrum by subtracting the spectrum from the mean spectrum for that night, normalizing to the latter. We then calculated the cross-correlation function between each difference spectrum and a standard template spectrum, which was a very high signal-to-noise spectrum of a slowly-rotating star (Procyon) of similar spectral type, obtained with the same instrument. The cross-correlation combines the information from all the bumps moving across all spectral lines (including rotationally-blended lines) into a single function of displacement from line center, thereby significantly increasing the signal-to-noise ratio of the moving features. Analysis of the time-series of cross-correlation functions yields the rate of propagation of features and their separation in velocity, which may be interpreted in terms of effective azimuthal wavenumber and oscillation frequency. Modes are identified by remapping the cross-correlation functions in terms of longitude and performing two-dimensional Fourier transforms. For each night a different modal pattern was found, usually with several modes. The modes have effective azimuthal order m ranging from about 2 up to about 12, and frequencies between 120 and 170 uHz (i.e., 2.3 to 1.6 hours), with frequency gradually increasing with increasing m. The relative amplitude of the different modes changes substantially from night to night, suggesting either that the coherence time of the modes is not longer than about a day, or that beats are being observed between modes of similar wavelength and frequency. Title: Speckle Observations of Mira's Companion Authors: Karovska, M.; Nisenson, P.; Beletic, J. Bibcode: 1993ApJ...402..311K Altcode: We present the first speckle interferometric observations of Mira's hot companion. The companion accretes mass from Mira's wind and provides an excellent opportunity for studying the accretion processes in detached binaries. The separation between the components of the system is crucial for accurate determination of the accretion rate onto the companion. Speckle measurements of the separation made at three epochs since 1983 with much higher precision than previous visual observations show that the companion's distance from Mira is substantially larger than expected. Title: An Advanced Fiber Optic Echelle Spectrograph for Asteroseismology Authors: Noyes, R. W.; Brown, T. M.; Horner, S.; Korzennik, S.; Nisenson, P. Bibcode: 1993ASPC...42..485N Altcode: 1993gong.conf..485N No abstract at ADS Title: The AFOE - a new instrument for asteroseismology Authors: Noyes, R. W.; Brown, T. M.; Horner, S.; Korzennik, S.; Nisenson, P. Bibcode: 1993ASPC...40..752N Altcode: 1993IAUCo.137..752N; 1993ist..proc..752N No abstract at ADS Title: Progress with the Infrared-Optical Telescope Array Authors: Benson, J. A.; Carelton, N. P.; Lacasse, Mg.; Nisenson, P.; Papaliolios, C.; Pearlman, M. R.; Reasenberg, R. D.; Traub, W. A.; Dyck, H. M.; Gibson, D. M.; Predmore, R.; Schloerb, F. P. Bibcode: 1992AAS...181.7405B Altcode: 1992BAAS...24.1239B No abstract at ADS Title: The Infrared Optical Telescope Array: Project Update Authors: Lacasse, M. G.; Carleton, N. P.; Nisenson, P.; Pearlman, M.; Reasenberg, R.; Traub, W. A.; Horowitz, P.; Papaliolios, C.; Gibson, D.; Predmore, R.; Schloerb, F. P.; Strom, S.; Dyck, M.; Ridgeway, S. Bibcode: 1992AAS...180.0912L Altcode: 1992BAAS...24..742L Smithsonian Astrophysical Observatory, Harvard University, University of Massachusets-Amherst, University of Wyoming and MIT Lincoln Laboratory are collaborating to construct and operate an Infrared Optical Telescope Array (IOTA) at the Smithsonian's Fred L. Whipple Observatory on Mt. Hopkins south of Tucson, AZ. The array will consist of 3 light collector assemblies each with apertures of 0.45 meter diameter on baselines of 5 to 38 meters. The array will operate in the optical (0.45microns to 0.75microns) and in the infrared (1.25microns to 2.2microns) as a Michelson interferometer. We present some of the design considerations which have led us to the current configuration of this instrument. We examine the current status of the fabrication and testing of varioussystems. We discuss some of the scientific targets which this instrument will uniquely be suited to investigate. Early investigations will focus on diameters of single stars and on orbital parameters for binary star systems. Of particular interest is the investigation of the diameter as a function of time and wavelength for radially pulsating stars such as Cepheids. In later investigations, we will investigate objects with more complex geometries such as multiple-star systems and disks around stars. We hope eventually to investigate the structure in the cores of the brightest active galactic nuclei. The construction phase of the project is nearing completion. The central building and the array-station foundations are under construction on Mt. Hopkins. The light collector assemblies are complete and being tested in Cambridge.Two elements of the array should see first light later this year. Title: Speckle View of Supernova 1987A and Longperiod Variables Authors: Karovska, M.; Nisenson, P. Bibcode: 1992ESOC...39..141K Altcode: 1992hrii.conf..141K No abstract at ADS Title: Single Speckle Frame Imaging Using Ayers-Dainty Blind Iterative Deconvolution Authors: Nisenson, P. Bibcode: 1992ESOC...39..299N Altcode: 1992hrii.conf..299N No abstract at ADS Title: Iterative deconvolution of x ray and optical SNR images Authors: Nisenson, Peter; Standley, Clive; Hughes, John Bibcode: 1992sao..reptR....N Altcode: Blind Iterative Deconvolution (BID) is a technique which was originally developed to correct the degrading effects of atmospheric turbulence on astronomical images from single short exposure, high signal-to-noise-ratio frames. At the Center for Astro physics, we have implemented a version of BID following the general approach of Ayers and Dainty (1988), but extending the technique to use Wiener filtering, and developed it for application to high energy images from Einstein and ROSAT. In the optical, the point spread function (PSF) that degrades the images is due to a combination of telescope and atmospheric aberrations. At high energies, the degrading function is the instrument response function, which is known to be time and energy level unstable. In both cases, the PSF is poorly known, so BID can be used to extract the PSF from the image and then deconvolve the blurred image to produce a sharpened image. Other aspects of this technique are discussed. Title: The effects of limb variation on the diameter measurements of SN 1987A. Authors: Karovska, M.; Nisenson, P. Bibcode: 1992A&A...253..210K Altcode: We explore the effects of model brightness distributions on the estimated diameter from measurements of the supernova SN 1987A envelope. The measurements were made using speckle interferometry techniques 265 days after the explosion. The results of this study show strong dependence of the diameter estimates for different model profiles. We conclude that the choice of the intensity distribution profile has an essential role in accurate determination of the supernova envelope diameter. Title: HST image processing: an overview of algorithms for image restoration Authors: Gonsalves, Robert A.; Nisenson, Peter Bibcode: 1991SPIE.1567..294G Altcode: After the Hubble Space Telescope was stabilized so that it could image a star, scientists were dismayed to find that the telescope produced severely degraded images. A flaw in the manufacture of the primary mirror causes an aberration that appears to be circularly symmetric. In this paper we review some of the algorithms and procedures that have been used to perform image restoration of the Hubble data. Title: Speckle Observations of Mira's Companion Authors: Karovska, M.; Nisenson, P.; Beletic, J. Bibcode: 1991BAAS...23.1380K Altcode: No abstract at ADS Title: Asymmetries in the Atmosphere of Mira Authors: Karovska, M.; Nisenson, P.; Papaliolios, C.; Boyle, R. P. Bibcode: 1991ApJ...374L..51K Altcode: A two-dimensional high angular resolution study of Omicron Ceti (Mira), carried out at four epochs from November 1983 to November 1988 using speckle interferometry techniques, detected asymmetries in the extended atmosphere of this pulsating star. The reconstructed speckle images show that the strength and the shape of this asymmetry changes as a function of wavelength and time. The position angles of the major axes of the asymmetries at different epochs are determined and the axes were measured accurately as a function of wavelength. The origin of the observed asymmetries has not yet been identified. Plausible causes include instabilities in the pulsating atmosphere, nonspherical pulsation, or the interaction with the nearby companion. Title: HST image processing - An overview of algorithms for image restoration Authors: Gonsalves, Robert A.; Nisenson, Peter Bibcode: 1991adip.proc..294G Altcode: An account is given of the algorithms that have been devised and the procedures that have been performed to achieve image restoration on the HST. The techniques employed are the inverse and Wiener filters, and the methods encompass those of constrained-iterative, Richardson-Lucy, blind deconvolution, and maximum entropy type. The blind deconvolution method is noted to be especially powerful. Title: A Wiener Filter Version of Blind Iterative Deconvolution Authors: Nisenson, P.; Standley, C.; Gay, D. Bibcode: 1991rhis.conf..103N Altcode: No abstract at ADS Title: Measurements of the Diameter of the Supernova SN 1987A Authors: Karovska, M.; Nisenson, P.; Standley, C.; Heathcote, S. R. Bibcode: 1991ApJ...367L..15K Altcode: We present speckle interferometric measurements of the angular diameter of SN 1987A in the Large Magellanic Cloud obtained at 664 days after the outburst. Diameters were estimated with milliarcsecond precision at 657 nm and 550 nm by fitting model visibility functions to the data corresponding to different intensity distributions for the supernova disk. Measurements made assuming a uniform intensity distribution were compared to the uniform disk measurements obtained from 30 days after the explosion. Diameter measurements obtained near the center of the Hα line are consistent with homologous expansion of the supernova shell with a mean velocity of 2850 km s^-1^. The linear least-squares fit to the measurements obtained at other wavelengths from 260 days after the explosion yielded a somewhat lower mean expansion velocity. Title: High resolution optical imaging through the atmosphere Authors: Noyes, R. W.; Nisenson, P.; Stachnik, R. V.; Papaliolios, C. Bibcode: 1989sao..rept.....N Altcode: This program has concentrated on three major areas: the application of high angular resolution image reconstruction techniques to the reconstruction of solar surface features; speckle imaging of a wide range of astronomical sources; and the implementation of adaptive optics for faint object imaging. Substantial modifications were made to a technique for reconstruction of high resolution images from single short exposure solar frames, blind iterative deconvolution (IDC). These improvements were tested using numerical simulation data. Analysis of speckle data of the supernova SN1987A has detected a new bright source, 0.9 arcseconds south of the SN, as well as substantial structure in the region surrounding the SN. New results were obtained on several Young Stellar Objects and supergiants. In the area of adaptive optics, an AOA wavefront sensor has been set up and tested using an image intensifier which increases its sensitivity by three orders of magnitude. Faint object image active tilt correction was also tested with some important enhancements, including new highly linear and sensitive CCD quad cells developed by Cal Tech and Tektronix, and an off-the-shelf high speed 2-D tilting mirror with greatly improved specifications. The effects of only partially correcting atmospheric turbulence have been theoretically analyzed and numerically simulated. Title: Astronomical Image Processing with Iterative Deconvolution Authors: Nisenson, P.; Standley, C.; Hughes, J. Bibcode: 1989BAAS...21.1072N Altcode: No abstract at ADS Title: Measurement of Limb-Darkening/Brightening and Asymmetry of Mira's Extended Atmosphere Authors: Karovska, M.; Nisenson, P.; Standley, C.; Heathcote, S. Bibcode: 1989BAAS...21.1117K Altcode: No abstract at ADS Title: A Second Generation PAPA Detector Authors: Standley, C.; Nisenson, P. Bibcode: 1989BAAS...21.1072S Altcode: No abstract at ADS Title: Supernova 1987A in the Large Magellanic Cloud Authors: Karovska, M.; Nisenson, P.; Standley, C.; Heathcote, S. Bibcode: 1989IAUC.4837....1K Altcode: 1989IAUC.4837....0K M. Karovska, P. Nisenson and C. Standley, Center for Astrophysics; and S. Heathcote, Cerro Tololo Interamerican Observatory, report: "New measurements of the diameter of SN 1987A were made from speckle data obtained at the CTIO 4-m telescope in 1988 Dec. (IAUC 4749) using a 35-nm bandpass centered at 551 nm. The diameters obtained at 657/7 nm and 551/35 nm are 0".042 +/- 0".002 and 0".046 +/- 0".002, respectively. The mean velocity of expansion calculated from these measurements is in agreement with previously reported measurements (2850 km/s: IAUC 4604). Reconstructed images from the 551/35 nm data reveal complex arclike structures within 2" of the supernova. The images clearly show the presence of a number of bright knots in the structures. These arcs are very similar to those described by Crotts et al. (IAUC 4791) in CCD images obtained in 1989 Mar. These images are suggestive of separated concentric rings around SN 1987A and may be due to a light echo or fluorescence from material located behind the supernova in two discrete shells. These shells could be a result of episodic mass loss during the red-supergiant stage of evolution of the progenitor star. If this interpretation is correct, one would expect to observe a contraction of the rings by the current epoch." Title: Supernova 1987A in the Large Magellanic Cloud Authors: Burrows, C.; Karovska, M.; Nisenson, P.; Standley, C.; Bailyn, C.; Heathcote, S. Bibcode: 1989IAUC.4781....1B Altcode: 1989IAUC.4781....0B C. Burrows, Space Telescope Science Institute; and Astrophysics Division, ESA Space Science Department, reports: "CCD coronagraphic images taken with the 2.2-m telescope at the European Southern Observatory on 1988 Sept. 8 contain 16 pointlike sources down to a limit of 20 mag in a 20" x 30" region centered on the supernova. All these sources appear consistent photometrically and astrometrically with sources present on the pre-explosion digitized plate No. 4858 referred to by Walborn et al. (1987, Ap.J. 321, L41). After subtraction of these sources, all the remaining structure in the field is consistent with fainter background stars present in both residual images. This shows that there is no apparent light echo with an annular morphology and a thickness of 1" to 3" in the angular range 5" to 10" from the supernova to a limit of R = 22 mag per square arcsec, and it appears inconsistent with a sheet or spherical shell of dust as being the cause of the inner echo reported by Bond et al. (IAUC 4733)." M. Karovska, P. Nisenson, C. Standley and C. Bailyn, Center for Astrophysics; and S. Heathcote, Cerro Tololo Interamerican Observatory, communicate: "The position of maximum brightness of SN 1987A determined from speckle (1988 Dec., IAUC 4749) and CCD (1989 Mar., IAUC 4753) images obtained at the CTIO 4-m telescope shows evidence for a displacement of 0".15 +/- 0".07 from the astrometric position of star 1 as measured by Testor (1987, A.Ap. 190, L1) and Heap et al. (1987, A.Ap. 185, L10) in the pre-explosion images of the Sk -69 202 complex. The possibility of extended structure around the supernova may result in an additional systematic error in the position of the supernova itself not included in the above error estimates. Analysis of pre-supernova plates suggested that star 1 may be composed of two stars (Testor; Heap et al.) separated in the north-south direction and allows a possibility that one of the components survived the explosion. Assuming the supernova itself continued to decay at the same rate as it did during the period from day 500 to approximately day 600, the change in slope after day 600 can be explained by the presence of the other star. In this case the visible lightcurve is well fit by including a star with V = 13.4, probably a supergiant of a spectral type between late A and early G. The pre-explosion magnitude of the B supergiant that became SN 1987A would then have been V = 12.8. Extrapolation of this fit predicts that the lightcurve will flatten out by mid-July." Title: Measurements of the Diameter of the Large Magellanic Cloud Supernova SN 1987A Authors: Karovska, M.; Koechlin, L.; Nisenson, P.; Papaliolios, C.; Standley, C. Bibcode: 1989ApJ...340..435K Altcode: We present direct measurements of the angular diameter of SN 1987A in the Large Magellanic Cloud (LMC) made from high-angular resolution observations at the CTIO 4 m telescope in five observing runs from 1987 April to 1988 April. Diameters were determined to milliarcsecond precision from integrated power spectra, using speckle interferometric data. The accuracy of the technique was evaluated by laboratory experiments and measurements of the diameters of several stars of known angular size. The SN 1987A diameters measured near the center of the Hα line show clear evolution during this period. The rate at which the supernova size changed at this wavelength corresponds to 2850 km s^-1^ mean velocity of expansion. Diameter measurements obtained in several spectral lines and in the continuum indicate stratification of the expanding envelope of the supernova. Our continuum data yield diameters substantially larger than those calculated from photometric measurements and a blackbody fit to the observed spectra. Title: Asymmetry of the envelope of supernova 1987A Authors: Papaliolios, C.; Karovska, M.; Koechlin, L.; Nisenson, P.; Standley, C.; Heathcote, S. Bibcode: 1989Natur.338..565P Altcode: 1989Nat...338..565P The supernova SN1987A in the Large Magellanic Cloud has been observed by high-angular-resolution speckle interferometry since 25 March (30 days after the explosion) with the 4-m telescope at the Cerro Tololo Interamerican Observatory. These observations have provided a number of results that may be central to a detailed understanding of this unique event. Data obtained on 25 March and 2 April 1987 revealed a second bright 'companion' source separated from the supernova by 60 milliarcseconds and less than three magnitudes fainter than the supernova1. Measurements of the average diameter of the supernova envelope have been made from data recorded from March 1987 to April 19882. Here we present a more detailed analysis of these data, which shows that the expanding envelope is asymmetric. This asymmetry has been observable since June 1987. The ratio between the minor and major axes of the envelope profile is about 2-3, and the position angle of the major axis is 20° +/- 5°, consistent with results reported from polarization measurements. The major axis is aligned with the position angle of the companion to the supernova. Title: High Angular Resolution Speckle Observations of SN1987A. Days 640 to 700 Authors: Karovska, M.; Nisenson, P.; Papaliolios, C.; Standley, C.; Heathcote, S. Bibcode: 1989BAAS...21..787K Altcode: No abstract at ADS Title: Supernova 1987A in the Large Magellanic Cloud Authors: Karovska, M.; Nisenson, P.; Papaliolios, C.; Standley, C.; Heathcote, S. Bibcode: 1989IAUC.4749....2K Altcode: 1989IAUC.4749....1K; 1989IAUC.4749....0K M. Karovska, P. Nisenson, C. Papaliolios, and C. Standley, Center for Astrophysics; and S. Heathcote, Cerro Tololo Interamerican Observatory, write: "Observations performed on 1988 Dec. 20 with the CTIO 4-m telescope, the PAPA detector, and speckle image reconstruction techniques show a source located 0".85 +/- 0".05 from SN 1987A at position angle 200 +/- 5 deg. The magnitude difference of this source from the SN is approximately 2.6 in a 35-nm bandpass centered at 551 nm. The separation and p.a. of this source is consistent with the position of the compact blob reported by Allen et al. (IAUC 4747). It is also consistent with a position predicted for uniform motion of the bright source which was detected using speckle techniques on 1987 Apr. 1 (IAUC 4382) and by Matcher et al. on 1987 Apr. 15 (IAUC 4413). We also detect star 2 (IAUC 4319) separated by 3" from the SN with a magnitude difference of about 3 (at 551 nm) and p.a. of 315 +/- 5 degrees. We do not see star 3 (IAUC 4322) in these observations, so it would have to be at least 4 mag fainter than the SN. We also do not detect any feature to the north of the SN, as suggested by Allen. These features should now be observable using direct imaging under good seeing conditions." Title: Supernova 1987A in the Large Magellanic Cloud Authors: Karovska, M.; Nisenson, P.; Papaliolios, C.; Standley, C.; Heathcote, S. Bibcode: 1989IAUC.4752....2K Altcode: 1989IAUC.4752....1K; 1989IAUC.4752....0K M. Karovska, P. Nisenson, C. Papaliolios, and C. Standley, Center for Astrophysics; and S. Heathcote, Cerro Tololo Interamerican Observatory, communicate: "Reduction of speckle data recorded on 1988 Nov. 28 and 1989 Jan. 20 confirms the existence of the bright source near SN 1987A reported on IAUC 4749 from observations on 1988 Dec. 20. The data were recorded with the CTIO 4-m telescope, the PAPA detector, and a 35-nm bandpass centered at 551 nm. The source was located at p.a. 200 +/- 5 deg for all observations. Preliminary estimates of the magnitude differences (from the SN) and angular separations were: 3.3 +/- 0.2 mag and 0".85 +/- 0".05 (Nov. 28); and 2.1 +/- 0.2 mag and 0".95 +/- 0".05 (Jan. 20). The Dec. result showed that the source was 2.6 +/- 0.2 mag different from the SN and separated by 0".85 +/- 0".05. Data recorded at other wavelengths are currently being reduced." Title: The Iota Project Authors: Carleton, N.; Horowitz, P.; Lacasse, M.; Nisenson, P.; Papaliolios, C.; Reasenberg, R.; Traub, W.; Predmore, R.; Schloerb, P.; Strom, S.; Gibson, D.; Benson, J.; Dyck, M. Bibcode: 1989BAAS...21..709C Altcode: No abstract at ADS Title: Evidence for asymmetries in SN1987A Authors: Karovska, M.; Koechlin, L.; Nisenson, P.; Papaliolios, C.; Standley, C. Bibcode: 1989HiA.....8..193K Altcode: No abstract at ADS Title: Speckle Imaging with the PAPA Detector and the Knox-Thompson Algorithm Authors: Nisenson, P. Bibcode: 1989ASIC..274..157N Altcode: 1989dli..conf..157N No abstract at ADS Title: High Angular Resolution Speckle Observations of SN1987A: Days 40 to 580 Authors: Karovska, M.; Nisenson, P.; Papaliolios, C.; Standley, C. Bibcode: 1988BAAS...20..961K Altcode: No abstract at ADS Title: Two-Dimensional 5μm Speckle Interferometry of IRC + 10216 Authors: Nisenson, P.; Stachnik, R.; Gezari, D. Bibcode: 1988BAAS...20.1014N Altcode: No abstract at ADS Title: High Spatial Resolution Observations of Young Stellar Objects Authors: Salas, L.; Strom, S.; Edwards, S.; Stauffer, J.; Nisenson, P.; Karovska, M. Bibcode: 1988BAAS...20R1091S Altcode: No abstract at ADS Title: The Measurement of Stellar Angular Diameters Smaller than the Telescope's Diffraction Limit Authors: Standley, C.; Karovska, M.; Nisenson, P.; Papaliolios, C. Bibcode: 1988BAAS...20R1005S Altcode: No abstract at ADS Title: Supernova 1987A in the Large Magellanic Cloud Authors: Karovska, M.; Koechlin, L.; Nisenson, P.; Papaliolios, C.; Standley, C. Bibcode: 1988IAUC.4604....1K Altcode: 1988IAUC.4604....0K M. Karovska, L. Koechlin, P. Nisenson, C. Papaliolios and C. Standley, Center for Astrophysics, report: "New measurements have been made of SN 1987A, showing a substantial asymmetry in the expanding shell. Speckle interferometric processing was applied to data that were recorded using the CTIO 4-m telescope and our PAPA camera speckle system during Feb. 29-Mar. 2 and Apr. 9-12. Data were recorded in 10-nm passbands at several wavelengths. We report on results obtained at two wavelengths, 533 nm and 656 nm (H alpha). Previous diameter measurements were reported on IAUC 4521 and 4457. For those data, azimuthal averages of the power spectra were performed, and Airy disks were fitted. These new data are of better quality than the earlier data, mostly due to better seeing. The higher signal-to-noise and increased size of the shell have allowed greater accuracy in the measurements. A substantial asymmetry is observed in displays of the power spectra and in the image reconstructions. The images are elongated along an axis tilted about 20 degrees from north. The image is 20 to 30 percent longer along this axis and is somewhat brighter in the southwest direction. Similar asymmetries have been detected in previous observations, but the poorer signal-to-noise in those data and the smaller scale of the SN at the time precluded accurate measurements of the effect. A summary of the results follows. The azimuthally averaged diameter in Feb.-Mar. was 0".019 at 533 nm and 0".020 at 656 nm. In Apr. the diameter was 0".026 at 533 and 0".027 at 656 nm. The 1-sigma error bars in these measurements are about 0".001. The Feb.-Mar. data give a 0".017 minor axis and 0".025 major axis (+/- 0".002). In April the minor axis was 0".025 and the major axis 0".030 (+/- 0".002). Data recorded on comparison stars gave symmetric power spectra and images and were unresolved (< 0".001 angular diameter). New measurements of Alpha Cen A give a diameter of 0".010 +/- 0".001, and the images show no asymmetry. Photometric estimates for Alpha Cen give a diameter of 0".009." Title: The Precision Calcium Photometer - a New Instrument for Asteroseismology Authors: Nisenson, P.; Dupree, A. K.; Noyes, R. W. Bibcode: 1988IAUS..123..521N Altcode: The Precision Calcium Photometer has been built with characteristics optimized for amplitude astroseismology. A description of the instrument and of laboratory and on-telescope test runs are discussed here. Title: Detection of a Very Bright Source Close to the LMC Supernova SN 1987A: Erratum Authors: Nisenson, P.; Papaliolios, C.; Karovska, M.; Noyes, R. Bibcode: 1988ApJ...324L..35N Altcode: In the Letter "Detection of a Very Bright Source Close to the LMC Supernova SN 1987A" by P. Nisenson, C. Papaliolios, M. Karovska, and R. Noyes (1987 Ap. J. [Letters], 320, L15), two of the figure labels for Figure 1 were inadvertently transposed in the production process. A corrected version of the figure appears as Plate L4. The Journal regrets the error. Title: High angular resolution observations of SN 1987A. Authors: Nisenson, P.; Karovska, M.; Koechlin, L.; Papaliolios, C.; Standley, C. Bibcode: 1988ESOC...29..491N Altcode: 1988hrii.conf..491N Using the 4-meter telescope at the Cerro Tololo Interamerican Observatory, and the technique of speckle interferometry, the authors have discovered an unexpected second bright source close to SN 1987A and they have measured the diameter of the expanding shell. Title: Speckle Imaging with the PAPA Detector and the Knox-Thompson Algorithm Authors: Nisenson, P. Bibcode: 1988dli..conf..157N Altcode: No abstract at ADS Title: SN 1987A and companion. Authors: Papaliolios, Costas; Karovska, Margarita; Nisenson, Peter; Standley, Clive Bibcode: 1988slmc.proc..225P Altcode: The diameter of the shell surrounding SN 1987A was measured using the technique of Davis and Tango (1986). Also, the position of the supernova relative to Sanduleak -69 deg 202 was determined and the area around SN 1987A was examined to search for reflected light. It is found that SN 1987A has a faint companion. The data concerning the magnitude and position of the companion on March 25 and April 4, 1987 are given. In addition, the measured diameter of SN 1987A is presented for several wavelengths between 450 and 775 nm observed on April 2 and June 1, 1987. Title: Supernova 1987A in the Large Magellanic Cloud Authors: Karovska, M.; Koechlin, L.; Nisenson, P.; Papaliolios, C.; Standley, C.; Beresford, A. C. Bibcode: 1987IAUC.4521....1K Altcode: 1987IAUC.4521....0K M. Karovska, L. Koechlin, P. Nisenson, C. Papaliolios and C. Standley, Center for Astrophysics, report: "New measurements have been made of the angular diameter of SN 1987A using speckle interferometric techniques. The data were recorded on Nov. 17-18 using the 4-m telescope at Cerro Tololo Interamerican Observatory and our PAPA camera speckle system. Data were recorded in 10-nm passbands at 533, 640, 656.5, 658.5 and 700 nm. Data were also recorded at 850 nm with a 250-nm passband. Count rates were adjusted using neutral-density filters to a level of 50 000 to 70 000 detected photons per second. The supernova had a visual magnitude of about 5.5 at that time. The result of least-squares fitting of Airy disks to the integrated power spectra gives the following diameters: 533 nm, 0".021; 640 nm, 0".020; 656.5 nm, 0".023; 700 nm, 0".024; 850 nm, 0".023. All results have an error of 0".002. Our measurements made on a G8 star, BS 1008, whose diameter has been estimated from the blackbody calculation to be 0".019, give a diameter of 0".019 +/- 0".002. We have also applied the same technique to comparison stars recorded with the supernova data, and all results show these stars to be unresolved, as expected. The result at 656.5 nm, when combined with earlier data sets, appears to fit a linear expansion velocity of 4000 km/s at 50 kpc, which may well be a direct measure of the photospheric expansion. The measured diameter is substantially larger than the value that would be obtained using a blackbody fit to the spectrum, but such a calculation is only applicable to stars without extended atmospheres." Visual magnitude estimates by A. C. Beresford, Adelaide, South Australia: Dec. 24.46 UT, 6.2; 25.48, 6.3; 27.50, 6.4; 28.49, 6.4. Title: Partial atmospheric correction with adaptive optics. Authors: Nisenson, Peter; Barakat, Richard Bibcode: 1987JOSAA...4.2249N Altcode: 1987OSAJ....4.2249N The authors have performed some one-dimensional numerical simulations to test atmospheric wave-front correction when the active element is not matched to the correlation scale in the pupil. The results demonstrate that substantial seeing improvement can be obtained with an adaptive optical system having a limited number of active elements. Title: Supernova 1987A in the Large Magellanic Cloud Authors: Karovska, M.; Nisenson, P.; Papaliolios, C.; Standley, C.; Beresford, A. C. Bibcode: 1987IAUC.4450....1K Altcode: 1987IAUC.4450....0K M. Karovska, P. Nisenson, C. Papaliolios and C. Standley, Center for Astrophysics, report: "The angular diameter of SN 1987A has been determined at three wavelengths from high angular resolution speckle data obtained on Apr. 2 and at four wavelengths from data recorded on June 1. These dates were 38 and 98 days, respectively, after the explosion. Observations were made with the CTIO 4-m telescope and our speckle camera using the PAPA 2-dimensional photon-counting detector. Data were recorded in 10-nm passbands centered at 450, 533 and 656 nm (H alpha) on both nights and at 775 nm on June 1. Approximately 30 000 speckle frames were used in each speckle integration for the SN data sets and the corresponding comparison star data. The power spectra were first azimuthally averaged, and then the SN power spectra were deconvolved with the comparison-star power spectra. We performed a least-squares fit of the Fourier transform of a uniform disk to the deconvolved SN power spectra. On Apr. 2, at a wavelength of 450 nm, the angular diameter was 0".010 +/- 0".003, which translates into a linear diameter of 500 AU (at a distance of 50 kpc) and gives an expansion velocity of 11 400 km/s; at 533 nm, angular diameter 0".011 +/- 0".004, linear diameter 550 AU, velocity 12 500 km/s; at 656 nm, angular diameter 0".001 +/- 0".004. On June 1 the corresponding figures were at 450 nm, 0".019 +/- 0".003, 950 AU, 8400 km/s; at 533 nm, 0".018 +/- 0".004, 900 AU, 8000 km/s; at 656 nm, 0".009 +/- 0".004, 450 AU, 4000 km/s; and at 775 nm, 0".022 +/- 0".005, 1100 AU, 9700 km/s." Visual magnitudes by A. C. Beresford, Adelaide, S. Australia: Sept. 15.41, 5.1; 16.47, 5.2; 17.47, 5.2; 18.41, 5.3; 19.50, 5.2. Title: Supernova 1987A in the Large Magellanic Cloud Authors: Catchpole, R.; Glass, I.; Karovska, M.; Nisenson, P.; Papaliolios, C.; Standley, C.; Flower, T. F.; Seargent, D. A. J.; McNaught, R. H. Bibcode: 1987IAUC.4457....1C Altcode: 1987IAUC.4457....0C R. Catchpole, South African Astronomical Observatory, telexes: "Since it is possible that emission features, in particular the CO fundamental band at 4.8 microns, may contribute a significant fraction of the infrared excess in the M band reported by Allen, Whitelock and Catchpole on IAUC 4453, spectroscopic observations in this band are very important. An emission feature that may be due to the CO first overtone at 2.3 microns is seen in a circular- variable-filter spectrum taken by I. Glass on July 9." M. Karovska, P. Nisenson, C. Papaliolios and C. Standley, Center for Astrophysics, report: "The measurements of the diameter of SN 1987A on IAUC 4450 were erroneously scaled by a factor proportional to the observation wavelength. Correctly scaled values follow. Apr. 2: 450 nm, 0".012 +/- 0".004, 600 AU, 13 500 km/s; 533 nm, 0".011 +/- 0".004, 550 AU, 12 500 km/s; 656 nm, 0".001 +/- 0".004, -, -. June 1: 450 nm, 0".023 +/- 0".004, 1150 AU, 10 200 km/s; 533 nm, 0".018 +/- 0".004, 900 AU, 8000 km/s; 656 nm, 0".008 +/- 0".004, 400 AU, 3600 km/s; 775 nm, 0".015 +/- 0".004, 750 AU, 6700 km/s. As a calibration of the accuracy of our measurements of the diameter of SN 1987A, we measured the diameter of Alpha Cen using speckle data recorded at the CTIO 4-meter telescope with the PAPA speckle system. Data were recorded at 533 nm with a 10-nm bandpass. Fitting the Fourier transform of a uniform disk to the integrated power spectrum gives an angular diameter of 0".009 +/- 0".002. This is very close to the diameter of 0".0086 calculated by Blackwell and Shallis (1977, M.N. 180, 177)." Corrigendum. On IAUC 4452, in the second paragraph, the name of the observer should read T. F. Flower. Visual magnitudes: Sept. 23.56 UT, 5.6 (D. A. J. Seargent, The Entrance, N.S.W.); 24.77, 5.4 (R. H. McNaught, Coonabarabran, N.S.W.); 25.54, 5.4 (McNaught); 28.49, 5.5 (Seargent). Title: Detection of a Very Bright Source Close to the LMC Supernova SN 1987A Authors: Nisenson, P.; Papaliolios, C.; Karovska, M.; Noyes, R. Bibcode: 1987ApJ...320L..15N Altcode: High angular resolution observations of the supernova in the Large Magellanic Cloud, SN 1987A, have revealed a bright source separated from the SN by approximately 60 mas with a magnitude difference of 2.7 at 656 nm (H-alpha). Speckle imaging techniques were applied to data recorded with the CfA two-dimensional photon counting detector on the CTIO 4 m telescope on March 25 and April 2 to allow measurements in H-alpha on both nights and at 533 nm and 450 nm on the second night. The nature of this object is as yet unknown, though it is almost certainly a phenomenon related to the SN. Title: Supernova 1987A in the Large Magellanic Cloud Authors: Karovska, M.; Nisenson, P.; Papaliolios, C.; Standley, C. Bibcode: 1987IAUC.4440....2K Altcode: 1987IAUC.4440....1K; 1987IAUC.4440....0K M. Karovska, P. Nisensen, C. Papaliolios and C. Standley, Center for Astrophysics, report: "Follow-up observations were carried out during May 30-June 2 with the purpose of detecting the second bright source (IAUC 4382) using our speckle system and the CTIO 4-m telescope. Data were recorded in 10-nm bandpasses at H alpha and seven other optical wavelengths in the range 400-775 nm. Conditions were fairly good (2"-3" seeing) on two of the four nights. Careful analysis of these data has not provided a certain detection of the second source above the background noise. For a certain detection the magnitude difference at the time of these observations would have to be less than about 4. SN 1987A had brightened from mv about 4.1 at the time of our original observation (Mar. 23) to mv about 3.1 for these observations, so if the second source remained at its originally detected brightness the magnitude difference between it and the supernova would have been about 3.7. Data from additional observations carried out in early July using the same telescope and equipment are still being reduced. The positions of the second source relative to the supernova were remeasured in the reconstructions from data taken on Mar. 23 and Apr. 2. To the limits of accuracy of the process (0".015) there was no detectable change in the separation. Better accuracy in centroid determination might have been possible if the supernova were at a greater zenith angle, where atmospheric dispersion would have less of an effect." Title: Detection of a Very Bright Close Companion Source to SN1987A Authors: Nisenson, P.; Karovska, M.; Noyes, R.; Papaliolios, C. Bibcode: 1987BAAS...19..950N Altcode: No abstract at ADS Title: Supernova 1987A in the Large Magellanic Cloud Authors: Karovska, M.; Nisenson, P.; Noyes, R.; Papaliolios, C.; McNaught, R.; Seargent, D. A. J. Bibcode: 1987IAUC.4382....2K Altcode: 1987IAUC.4382....1K; 1987IAUC.4382....0K M. Karovska, P. Nisenson, R. Noyes, and C. Papaliolios, Center for Astrophysics, write: "High-angular-resolution speckle observations of SN 1987A on Mar. 25 and Apr. 2 using the Cerro Tololo Interamerican Observatory 4-m telescope (with the CfA PAPA photon- counting detector) show a bright feature with a separation of 0".057 +/- 0".014 at p.a. 194 deg +/- 5 deg relative to the SN. This feature appears to be 2.7 +/- 0.2 mag fainter than the SN in a 10-nm bandpass centered on 656.3 nm (H-alpha). A corresponding feature was detected in a 10-nm bandpass centered at 533 nm, though it appears to be somewhat fainter than in H-alpha. Preliminary analysis of data recorded in a 10- nm bandpass centered at 450 nm shows no evidence of an object within a 4-mag difference from the SN. Data from nearby comparison stars, recorded close in time using the same filters, produced clean, point-like images with no structure above the noise at the separation and position angle of the observed feature." Corrigendum. On IAUC 4370, lines 7-15, for mm read microns Visual magnitude estimates: Apr. 28.51 UT, 3.0 (R. McNaught, Siding Spring Observatory); 29.38, 3.0 (D. A. J. Seargent, The Entrance, N.S.W.); 30.43, 2.9 (McNaught). Title: High Angular Resolution Speckle Imaging of α Ori Authors: Karovska, M.; Nisenson, P.; Noyes, R. Bibcode: 1987BAAS...19..755K Altcode: No abstract at ADS Title: Speckle Imaging at CfA Authors: Nisenson, P.; Karovaka, M.; Noyes, R.; Papaliolios, C.; Stachnik, R.; Strom, S.; Edwards, S. Bibcode: 1987BAAS...19Q.748N Altcode: 1987BAAS...19..748N No abstract at ADS Title: Magnitude Limit of the Group Delay Fringe Tracking Method for Long Baseline Interferometry Authors: Nisenson, P.; Traub, W. Bibcode: 1987iia..conf..129N Altcode: No abstract at ADS Title: Speckle Imaging at CFA Authors: Nisenson, P.; Karovska, M. Bibcode: 1987iia..conf..229N Altcode: No abstract at ADS Title: The CERGA Small Interferometer Authors: Koechlin, L.; di Benedetto, G. P.; Thom, C.; Nisenson, P. Bibcode: 1987iia..conf..109K Altcode: Contents: 1. Stellar diameters at λ = 0.6 μm (1985 - 86). 2. Stellar diameters at λ = 2.2 μm and 1.6 μm. 3. γ Cassiopeiae envelope in the Hα emission line. 4. Observations of α Cyg with the PAPA detector at λ = 0.6 μm. Title: Resolution of the halo binary MU CAS at optical wavelengths. Authors: Karovska, M.; Nisenson, P.; Stachnik, R. V. Bibcode: 1986AJ.....92..898K Altcode: The faint secondary of the Population II binary system μ Cas has been detected at 850 nm, using a two-dimensional photon-counting camera and speckle-imaging techniques. The reconstructed image of the μ Cas binary system permitted a determination of the position angle (63°±2°) and separation (1arcsec.118±0arcsec.023) of μ Cas B, and its magnitude difference from the primary (Δm ≈ 5 at 850 nm). Using these results together with existing astrometric measurements the authors estimated the masses of the components. Since errors in the mass estimates are still dominated by errors in the astrometric data, no definitive estimate of the helium abundance could be derived. However, using mean values for the masses and Z = 0.005, the authors estimated Y = 0.21 for μ Cas A, which is consistent with their estimate of the helium abundance for μ Cas B (0.20 ≤ Y ≤ 0.25). Title: On the Alpha Orionis Triple System Authors: Karovska, M.; Nisenson, P.; Noyes, R. Bibcode: 1986ApJ...308..260K Altcode: Detection of two close optical companions to the red supergiant α Ori was accomplished in 1983 November on the Steward Observatory 2.25 m telescope. A new two-dimensional photon counting camera was used for data recording, and speckle imaging was used for image reconstruction. The closer of the two sources is located at 0arcsec.06±0arcsec.01 from α Ori (P.A. = 273°), the more distant at 0arcsec.51±0arcsec.01 (P.A. = 278°). An analysis of these results and of earlier polarization data favors an interpretation in which the two optical sources are stellar companions to α Ori. Title: High Angular Resolution Speckle Observations of Mira Authors: Karovska, M.; Nisenson, P.; Stachnik, R. V. Bibcode: 1986BAAS...18..914K Altcode: No abstract at ADS Title: High Angular Resolution Solar Imaging by Post-processing Authors: Nisenson, P.; Stachnik, R. V. Bibcode: 1986BAAS...18..924N Altcode: No abstract at ADS Title: High resolution astrophysical observations using speckle imaging Authors: Noyes, R. W.; Nisenson, P.; Papaliolios, C.; Stachnik, R. V. Bibcode: 1986sao..reptQ....N Altcode: This report describes progress under a contract to develop a complete astronomical speckle image reconstruction facility and to apply that facility to the solution of astronomical problems. During the course of the contract we have developed the procedures, algorithms, theory and hardware required to perform that function and have made and interpreted astronomical observations of substantial significance. A principal result of the program was development of a photon-counting camera of innovative design, the PAPA detector. Development of this device was, in our view, essential to making the speckle process into a useful astronomical tool, since the principal impediment to that circumstance in the past was the necessity for application of photon noise compensation procedures which were difficult if not impossible to calibrate. The photon camera made this procedure unnecessary and permitted precision image recovery. The result of this effort and the associated algorithm development was an active program of astronomical observation which included investigations into young stellar objects, supergiant structure and measurements of the helium abundance of the early universe. We have also continued research on recovery of high angular resolution images of the solar surface working with scientists at the Sacramento Peak Observatory in this area. Title: Development of a CCD based solar speckle imaging system Authors: Nisenson, Peter; Stachnik, Robert V.; Noyes, Robert W. Bibcode: 1986sao..reptR....N Altcode: A program to develop software and hardware for the purpose of obtaining high angular resolution images of the solar surface is described. The program included the procurement of a Charge Coupled Devices imaging system; an extensive laboratory and remote site testing of the camera system; the development of a software package for speckle image reconstruction which was eventually installed and tested at the Sacramento Peak Observatory; and experiments of the CCD system (coupled to an image intensifier) for low light level, narrow spectral band solar imaging. Title: Companions to α Orionis Authors: Karovska, M.; Nisenson, P.; Noyes, R. W.; Stachnik, R. Bibcode: 1986LNP...254..445K Altcode: 1986csss....4..445K Detection of two close optical companions to the red supergiant a Ori was accomplished using the PAPA detector for data recording, and speckle imaging for image reconstruction. Our analysis favors an interpretation in which the two optical sources are stellar companions to a Ori.The observed time dependent variations of the polarization of a Ori can be interpreted as being due to a systemic asymmetry created by one of the companions. Title: A new optical source associated with T Tauri. Authors: Nisenson, P.; Stachnik, R. V.; Karovska, M.; Noyes, R. Bibcode: 1985ApJ...297L..17N Altcode: A faint optical source close to T Tauri has been detected using speckle imaging techniques in a photon-counting mode of operation. This second optical source is located at position angle 358°±5° with a separation of 0arcsec.27±0arcsec.04 from the optical astrometric position of T Tauri. The visual magnitude difference with respect to the primary, measured at 521 nm, is mv = 4.33±0.09. Since the new source is located north of T Tauri, it is distinct from the radio/infrared object recently reported to be located 0arcsec.61 south of T Tauri. If the new source is a stellar object, it appears to have a mass of between 0.2 and 0.35 M_sun; and has a surface temperature of 3000±200K. Title: Speckle Image Reconstruction of a Northern Optical Companion to T Tau Authors: Nisenson, P.; Karovska, M.; Stachnik, R.; Noyes, R. Bibcode: 1985BAAS...17..556N Altcode: No abstract at ADS Title: On a Possible Close Companion to αOri Authors: Karovska, M.; Noyes, R. W.; Roddier, F.; Nisenson, P.; Stachnik, R. V. Bibcode: 1985BAAS...17..598K Altcode: No abstract at ADS Title: T Tauri Authors: Karovska, M.; Nisenson, P.; Noyes, R.; Papaliolios, C.; Stachnik, R. Bibcode: 1985IAUC.4039....2K Altcode: 1985IAUC.4039....0K M. Karovska, P. Nisenson, R. Noyes, C. Papaliolios and R. Stachnik, Center for Astrophysics, write: "Speckle image reconstructions of T Tau show a second, unresolved source located ~ 0"35 from T Tau at p.a. ~ 5 deg. The source was first detected at the Steward Observatory's 2.3-m telescope in 1983 Nov., and it was detected again using the 2.5-m telescope at Mt. Wilson Observatory in 1984 Nov., thus confirming its reality. Both sets of data were obtained through broad-band filters centered near 660 nm (and including H=alpha), using a two-dimensional photon-counting PAPA detector. The source appears to be ~ 4 mag fainter than T Tau itself in this wavelength band. We note that this appears to be a third component of the T Tau system; it is not the object reported by infrared and radio observers as being south of T Tau. Further optical or infrared observations of T Tau during the remainder of this observing season would be most useful." Title: Speckle imaging with the PAPA detector Authors: Papaliolios, Costas; Nisenson, Peter; Ebstein, Steven Bibcode: 1985ApOpt..24..287P Altcode: No abstract at ADS Title: Is Mt. Wilson the Best Interferometric Site in the World? Authors: Nisenson, P.; Noyes, R.; Shao, M. Bibcode: 1984BAAS...16..908N Altcode: No abstract at ADS Title: PM. 03 A 50-Meter Michelson Stellar Interferometer on a Space Platform Authors: Faucherre, M.; Lacasse, M. G.; Nisenson, P.; Reasenberg, R. D.; Shao, M.; Stachnik, R. V.; Traub, W. A. Bibcode: 1984BAAS...16..793F Altcode: The authors discuss a 50-meter Michelson stellar interferometer that could be mounted on a space platform. For this device, the estimated magnitude limit would be near +15 mag and, in the ultraviolet (2000 Angstroms), upper limits on angular diameters may be determined down to about 0.2 milliarcsecond. The authors regard the development of such a relatively simple, low-cost device as an important demonstration of the technical and scientific potential of long baseline optical interferometers in space. Title: Speckle with PAPA Authors: Nisenson, P.; Papaliolios, C.; Stachnik, R.; Ebstein, S. Bibcode: 1984BAAS...16..496N Altcode: No abstract at ADS Title: Finite Exposure Time, Astronomical Speckle Transfer Function Authors: Barakat, Richard; Nisenson, Peter Bibcode: 1983AcOpt..30.1405B Altcode: No abstract at ADS Title: Speckle image reconstruction of solar features Authors: Stachnik, R. V.; Nisenson, P.; Noyes, R. W. Bibcode: 1983ApJ...271L..37S Altcode: Speckle image reconstruction procedures have been applied to 5 x 6 arcsec patches of the solar surface. Data were recorded with a CID (charge-injection device) sensor. This detector has the wide dynamic range and linearity required to record accurately the extremely low contrast speckle that occurs for extended objects such as the sun. Reconstructed images of spot penumbrae and of pores show evidence for detail at scales as fine as 0.11 arcsec, despite prevailing seeing conditions of 1 - 2 arcsec. The finest structures appear to be embedded in penumbral filaments. Coarser sub-arcsecond detail appears in some, but not all, of the pores studied. The presence of such fine, presumably magnetically controlled detail suggests that much can be learned from high-resolution solar surface imaging from space. Title: Solar Speckle Imaging with a CCD Camera Authors: Nisenson, P.; Stachnik, R.; Noyes, R.; Ebstein, S. Bibcode: 1983BAAS...15..718N Altcode: No abstract at ADS Title: Speckle imaging for planetary research Authors: Nisenson, P.; Apt, J.; Goody, R.; Papaliolios, C. Bibcode: 1983Icar...53..465N Altcode: The use of speckle imaging techniques for planetary research is discussed. Data are gathered with a video camera system. Image reconstruction uses a division algorithm for Fourier amplitudes and the Knox-Thompson algorithm for Fouroer phases. Bias correction techniques for arbitrary "photon shapes" have been developed. Results have been obtained with a laboratory optical simulator and on Io, Titan, Pallas, Jupiter, and Uranus using the 2.24-m telescope on Mauna Kea. All evidence indicates that spatial resolutions less than the seing limit by a factor of about 4 can be obtained. This applies to objects brighter than Uranus. For fainter objectsbias correction is inadequate and images cannot be recovered. Resolutions obtained are well above the diffraction limit. The reasons for this performance are understood in terms of inadequacies in the video camera. A photon-counting camera has been developed which should eliminate these problems. If so, it should be possible to obtain diffraction-limited resolution on objects as faint as Charon. Title: Effects of photon noise on speckle image reconstruction with the Knox-Thompson algorithm. Authors: Nisenson, P.; Papaliolios, C. Bibcode: 1983OptCo..47...91N Altcode: An analysis of the effects of photon noise on astronomical speckle image reconstruction using the Knox-Thompson algorithm is presented. It is shown that the quantities resulting from the speckle average are biased, but that the biases are easily estimated and compensated. Calculations are also made of the convergence rate for the speckle average as a function of the source brightness. An illustration of the effects of photon noise on the image recovery process is included. Title: The effectiveness of astronomical speckle transfer function reweighting algorithms. Authors: Barakat, R.; Nisenson, P. Bibcode: 1983OptCo..45..311B Altcode: Two methods for reweighting the astronomical speckle transfer function are compared using a combination of analysis and numerical computation. One method, long exposure subtraction, is shown to perform well only for very short wavefront correlation lengths (shorter than the correlation length expected from a real atmosphere). The other method, reference star division, is demonstrated to be effective and accurate, even when the wavefront statistics for the reference star data are substantially changed from the object data statistics. An experimental result using real telescope data is included which substantiates the analysis. Title: Speckle Image Reconstruction of Solar Features Authors: Stachnik, R. V.; Nisenson, P.; Noyes, R. W. Bibcode: 1982BAAS...14R.624S Altcode: No abstract at ADS Title: Radius and limb darkening of Titan from speckle imaging. Authors: Nisenson, P.; Apt, J.; Goody, R.; Horowitz, P. Bibcode: 1981AJ.....86.1690N Altcode: The radius R of Titan is determined from ground-based, visible light observations using a two-dimensional speckle imaging technique. The value of R is found to depend on the limb-darkening exponent alpha, which is used in modeling the observed disk, and it is determined that the probable range extends from R values of 2680 + or - 100 km for alpha of 0.6 to 2900 + or - 100 km for alpha of 1.3. This range is in agreement with Voyager 1 and Pioneer Saturn observations. It is suggested that spatial resolution may be doubled by using a grid of 256 x 256 pixels at the time the image is digitized, and that further improvements are possible with speckle-reduction techniques under development. Title: Influence of the wave-front correlation function and deterministic wave-front aberrations on the speckle image-reconstruction problem in the high-light-level regime Authors: Barakat, R.; Nisenson, P. Bibcode: 1981JOSA...71.1390B Altcode: 1981OSAJ...71.1390B No abstract at ADS Title: High Resolution Image Reconstruction of Binary Stars and Other Objects Authors: Nisenson, P.; Stachnik, R. S. Bibcode: 1981BAAS...13..514N Altcode: No abstract at ADS Title: Solar Speckle Imaging Authors: Stachnik, R.; Nisenson, P.; Papaliolios, C. Bibcode: 1981siwn.conf..502S Altcode: No abstract at ADS Title: Data recording and processing for speckle image reconstruction. Authors: Nisenson, P.; Stachnik, R.; Papaliolios, C.; Horowitz, P. Bibcode: 1980SPIE..243...88N Altcode: Image reconstruction from astronomical speckle data using the Knox-Thompson algorithm has now been extensively demonstrated as feasible through analysis and computer simulations. Experimental verification of the technique and its implementation for astronomy places stringent constraints on the recording system and requires complex processing algorithms to handle the many experimental details. In this paper we describe a video recording system specifically designed for the requirements of speckle imaging. This system has been built and tested, yielding high quality image reconstructions from a laboratory-atmospheric simulator for a wide range of input light levels and test objects. Title: High Resolution Imaging at Large Telescopes Authors: Nisenson, P.; Stachnik, R.; Papaliolios, C.; Hewitt, A. Bibcode: 1980oits.conf..401N Altcode: 1980STIN...8029217N Image recovery at a resolution limited only by diffraction is now possible at large telescopes. The theory of speckle image reconstruction is explained and the current status of a video recording and digitization system for the reconstruction procedure is described. Potential applications of the process when used with very large telescopes are discussed. The constraints on telescope design imposed by these techniques are listed. Title: Image Reconstruction of Binary Stars and Solar Features Authors: Stachnik, R.; Nisenson, P.; Papaliolios, C. Bibcode: 1979BAAS...11..686S Altcode: No abstract at ADS Title: Speckle Image Reconstruction at Low Light Levels Authors: Nisenson, P.; Stachnik, R.; Papaliolios, C. Bibcode: 1979BAAS...11..668N Altcode: No abstract at ADS Title: Restoration of turbulence degraded images - A review Authors: Nisenson, P.; Stachnik, R. V. Bibcode: 1979hars.proc...34N Altcode: 1979IAUCo..50...34N The paper surveys techniques for recovering high resolution information from atmospheric turbulence degraded images. Several approaches to image restoration are covered, noting that the effectiveness of each technique is strongly dependent on the brightness and the angular extent of the object being observed. These approaches include: speckle holography and betelgence imaging, nonredundant aperture imaging, phase retrieval, and speckle imaging. In addition, the applications and the expected performance range of the various techniques are discussed. Title: Speckle Image Reconstruction of Astronomical Objects Authors: Nisenson, P.; Stachnik, R. V. Bibcode: 1978BAAS...10..661N Altcode: No abstract at ADS Title: Speckle Image Reconstruction of Outer Planet Satellites. Authors: Nisenson, P.; Stachnik, R. V. Bibcode: 1978BAAS...10..459N Altcode: No abstract at ADS Title: Measurements of atmospheric isoplanatism using speckle interferometry. Authors: Nisenson, P.; Stachnik, R. V. Bibcode: 1978JOSA...68..169N Altcode: 1978OSAJ...68..169N Measurements of isoplanatism for speckle interferometry and speckle imaging applications have been made at a 1.57 meter aperture telescope in Hawaii. The measurements were obtained from optically produced spatial power spectra of short-exposure images showing pairs of stars with different angular separations. The result of this process is a sequence of plots of correlation versus spatial frequency in the image for 0.25, 0.5, 1.9, and 4.7 arcsec separation binary stars. Substantial correlation is found to be at least 0.6 of the diffraction limit cutoff for the 4.7 arcsec pair. Title: Speckle image reconstruction of solar features Authors: Stachnik, R. V.; Nisenson, P.; Ehn, D. C.; Hudgin, R. H.; Schirf, V. E. Bibcode: 1977Natur.266..149S Altcode: SPECKLE imaging is a process which permits recovery of diffraction limited resolution from atmospherically degraded astronomical images. We describe here the application of this new process to the reconstruction of solar surface features with resolution approaching the telescope limit, despite severe atmospheric blurring in the original data. Title: Measurements of atmospheric isoplanatism using speckle interferometry. Authors: Nisenson, P.; Stachnik, R. V. Bibcode: 1977JOSA...67.1391N Altcode: 1977OSAJ...67.1391N No abstract at ADS Title: Measurements of the isoplanatic angle using speckle interferometry. Authors: Nisenson, P.; Stachnik, R. V. Bibcode: 1976JOSA...66.1077N Altcode: 1976OSAJ...66.1077N No abstract at ADS Title: Astronomical speckle imaging. Authors: Nisenson, P.; Ehn, D. C.; Stachnik, R. V. Bibcode: 1976SPIE...75...83N Altcode: 1976imat.conf...83N Speckle imaging is a technique for recovering diffraction limited images from sequences of atmosphere-degraded, short exposure photographs obtained at a large telescope. The technique is derived from speckle interferometry and shares many of the characteristics of that process, including dependence of the output signal-to-noise on number of frames processed and relative insensitivity to fixed telescope aberrations and noise in the image record. Speckle interferometry has been demonstrated to yield telescope-diffraction-limited information, but only in the form of spatial power spectra. Speckle imaging averages a different quantity, the statistical autocorrelation of the image Fourier transform, which contains all the information in the averaged power spectra plus the transform phase information required to recover an image. Two-dimensional digital simulations of the process for extended continuous-tone objects are presented, and include the case where severe static telescope aberrations are present. Title: Astronomical speckle imaging. Authors: Ehn, D. C.; Nisenson, P. Bibcode: 1975JOSA...65.1196E Altcode: 1975OSAJ...65.1196E No abstract at ADS Title: The PROM Optical Speckle Interferometer. Authors: Nisenson, P.; Stachnik, R. V. Bibcode: 1974BAAS....6..459N Altcode: No abstract at ADS Title: Mirror blank testing by real-time holographic interferometry. Authors: van Deelen, W.; Nisenson, P. Bibcode: 1969ApOpt...8..951V Altcode: No abstract at ADS