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Author name code: cavallini
ADS astronomy entries on 2022-09-14
author:"Cavallini, Fabio"
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Title: A Prototype of a Large Tunable Fabry-Pérot Interferometer
for Solar Spectroscopy
Authors: Greco, V.; Sordini, A.; Cauzzi, G.; Cavallini, F.; Del
Vecchio, C.; Giovannelli, L.; Berrilli, F.; Del Moro, D.; Reardon,
K.; Pietraszewski, K. A. R. B.
2022PASP..134a5007G Altcode: 2021arXiv211202224G
Large Fabry-Pérot Interferometers (FPIs) are used in a variety of
astronomical instrumentation, including spectro-polarimeters for 4 m
class solar telescopes. In this work we comprehensively characterize
the cavity of a prototype 150 mm FPI, sporting a novel, fully symmetric
design. Of particular interest, we define a new method to properly
assess the gravity effects on the interferometer's cavity when the
system is used in either the vertical or horizontal configuration,
both typical of solar observations. We show that the symmetric design
very effectively limits the combined effects of pre-load and gravity
forces to only a few nm over a 120 mm diameter illuminated surface,
with gravity contributing ~2 nm peak-to-valley (~0.3 nm rms) in either
configuration. We confirm a variation of the tilt between the plates
of the interferometer during the spectral scan, which can be mitigated
with appropriate corrections to the spacing commands. Finally, we show
that the dynamical response of the new system fully satisfies typical
operational scenarios. We conclude that large, fully symmetric FPIs
can be safely used within solar instrumentation in both, horizontal
and vertical position, with the latter better suited to limiting the
overall volume occupied by such an instrument.
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Title: New technique to measure the cavity defects of Fabry-Perot
interferometers
Authors: Greco, V.; Sordini, A.; Cauzzi, G.; Reardon, K.; Cavallini, F.
2019A&A...626A..43G Altcode: 2019arXiv190501393G
Context. Several astronomical instruments, for both nighttime and
solar use, rely on tunable Fabry-Perot interferometers (FPIs). Knowing
the exact shape of the etalons' cavity is crucial for assessing the
overall instrumental transmission profile and its possible variations
during the tuning process. <BR /> Aims: We aim to define and test
a technique to accurately measure the cavity defects of air-spaced
FPIs, including distortions due to the spectral tuning process that
are typical of astronomical observations. We further aim to develop a
correction technique to maintain the shape of the cavity as constant as
possible during the spectral scan. These are necessary steps to optimize
the spectral transmission profile of a two-dimensional spectrograph
(polarimeter) using one or more FPIs in series, and to ensure that
the spectral transmission profile remains constant during typical
observing conditions. <BR /> Methods: We devised a generalization of the
techniques developed for the so-called phase-shifting interferometry to
the case of FPI. This measuring technique is applicable to any given FPI
that can be tuned via changing the cavity spacing (z-axis), and can be
used for any etalon regardless of the coating' reflectivity. The major
strength of our method is the ability to fully characterize the cavity
during a spectral scan, allowing for the determination of scan-dependent
modifications of the plates. We have applied the measuring technique to
three 50 mm diameter interferometers, with cavity gaps ranging between
600 μm and 3 mm, coated for use in the visible range. <BR /> Results:
The technique developed in this paper allows us to accurately and
reliably measure the cavity defects of air-spaced FPIs, and of their
evolution during the entire spectral scan. Our main, and unexpected,
result is that the relative tilt between the two FPI plates varies
significantly during the spectral scan, and can dominate the cavity
defects; in particular, we observe that the tilt component at the
extremes of the scan is sensibly larger than that at the center of
the scan. Exploiting the capability of the electronic controllers to
set the reference plane at any given spectral step, we then develop
a correction technique that allows the minimization of the tilt
during a complete spectral scan. The correction remains highly stable
over long periods, well beyond the typical duration of astronomical
observations. <P />Movies attached to Figs. 6 and 13 are available at <A
href="https://www.aanda.org/10.1051/0004-6361/201935302/olm">https://www.aanda.org</A>
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Title: ADAHELI: exploring the fast, dynamic Sun in the x-ray, optical,
and near-infrared
Authors: Berrilli, Francesco; Soffitta, Paolo; Velli, Marco; Sabatini,
Paolo; Bigazzi, Alberto; Bellazzini, Ronaldo; Bellot Rubio, Luis
Ramon; Brez, Alessandro; Carbone, Vincenzo; Cauzzi, Gianna; Cavallini,
Fabio; Consolini, Giuseppe; Curti, Fabio; Del Moro, Dario; Di Giorgio,
Anna Maria; Ermolli, Ilaria; Fabiani, Sergio; Faurobert, Marianne;
Feller, Alex; Galsgaard, Klaus; Gburek, Szymon; Giannattasio, Fabio;
Giovannelli, Luca; Hirzberger, Johann; Jefferies, Stuart M.; Madjarska,
Maria S.; Manni, Fabio; Mazzoni, Alessandro; Muleri, Fabio; Penza,
Valentina; Peres, Giovanni; Piazzesi, Roberto; Pieralli, Francesca;
Pietropaolo, Ermanno; Martinez Pillet, Valentin; Pinchera, Michele;
Reale, Fabio; Romano, Paolo; Romoli, Andrea; Romoli, Marco; Rubini,
Alda; Rudawy, Pawel; Sandri, Paolo; Scardigli, Stefano; Spandre,
Gloria; Solanki, Sami K.; Stangalini, Marco; Vecchio, Antonio;
Zuccarello, Francesca
2015JATIS...1d4006B Altcode:
Advanced Astronomy for Heliophysics Plus (ADAHELI) is a project concept
for a small solar and space weather mission with a budget compatible
with an European Space Agency (ESA) S-class mission, including launch,
and a fast development cycle. ADAHELI was submitted to the European
Space Agency by a European-wide consortium of solar physics research
institutes in response to the "Call for a small mission opportunity
for a launch in 2017," of March 9, 2012. The ADAHELI project builds
on the heritage of the former ADAHELI mission, which had successfully
completed its phase-A study under the Italian Space Agency 2007 Small
Mission Programme, thus proving the soundness and feasibility of
its innovative low-budget design. ADAHELI is a solar space mission
with two main instruments: ISODY: an imager, based on Fabry-Pérot
interferometers, whose design is optimized to the acquisition of
highest cadence, long-duration, multiline spectropolarimetric images
in the visible/near-infrared region of the solar spectrum. XSPO: an
x-ray polarimeter for solar flares in x-rays with energies in the 15
to 35 keV range. ADAHELI is capable of performing observations that
cannot be addressed by other currently planned solar space missions,
due to their limited telemetry, or by ground-based facilities, due to
the problematic effect of the terrestrial atmosphere.
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Title: Design of the optics for an imaging classic mount multi-etalon
spectro-polarimeter for the next generation of ground-based solar
telescopes
Authors: Greco, V.; Cavallini, F.
2011SPIE.8172E..19G Altcode: 2011SPIE.8172E..31G
In designing the optics of an imaging classic mount multi-étalon
spectro-polarimeter as a post-focus instrument for the next generation
of ground-based solar telescopes (Advanced Technology Solar Telescope,
European Solar Telescope), many constraints must be considered. The
large entrance pupil diameter of the telescope (4 m), the demanded large
field of view (>= 90 arcsec), high spectral resolving power (>=
200000), and limited field-dependent blue-shift of the instrumental
profile (<= 3 FWHM) require Fabry-Pérot interferometers of large
diameter (>= 200 mm), lighted by highly collimated beams. This
implies large optical elements and long optical paths. Moreover, to
use interference pre-filters, placed between the interferometers to
reduce the inter-reflections in axial-mount, with a relatively small
diameter (<= 70 mm), a "pupil adapter" should be included, with a
further increase of the optical path length. Although a multi-étalon
spectro-polarimeter works in quasi-monochromatic light, the Fraunhofer
lines of interest cover a wide range of wavelengths (850 nm - 1650
nm), demanding a good chromatic aberration control. Finally, a low
instrumental polarization (<= 0.5 %) is required to allow a high
polarimetric precision. In this paper a diffraction limited optical
solution is described, fulfilling all the above requirements in a
relative small volume.
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Title: The Fabry-Perot interferometer prototype for the ADAHELI
solar small mission
Authors: Berrilli, Francesco; Cocciolo, Martina; Giovannelli, Luca; Del
Moro, Dario; Giannattasio, Fabio; Piazzesi, Roberto; Stangalini, Marco;
Egidi, Alberto; Cavallini, Fabio; Greco, Vincenzo; Selci, Stefano
2011SPIE.8148E..07B Altcode: 2011SPIE.8148E...6B
ADAHELI ADvanced Astronomy for HELIophysics is a solar satellite
designed to investigate the fast dynamics of the solar photosphere and
chromosphere performing visible and NIR broad-band and monochromatic
observations of selected atomic lines. ADAHELI is an Italian Space
Agency (ASI) project, approved for a feasibility study within the
ASI Small Missions call. ISODY Interferometer for SOlar DYnamics is
a Gregorian telescope and its focal plane suite (FPS). The FPS is
composed of a high-resolution fast acquisition system, based upon a
tandem of Fabry-Pérot interferometers operating in the visible and
NIR regions on selected solar atmospheric lines, a broad band channel,
and a correlation tracker used as image stabilization system. In this
contribution we describe the Fabry-Pérot étalon prototype, based
on the capacitance-stabilised concept, realized in our laboratory
to perform preliminary mechanical and optical tests with a view to a
future Fabry-Pérot étalon prototype for space application.
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Title: The telescope and the double Fabry-Pérot interferometer for
the ADAHELI solar space mission
Authors: Greco, V.; Cavallini, F.; Berrilli, F.
2010SPIE.7731E..42G Altcode: 2010SPIE.7731E.131G
ADvanced Astronomy for HELIophysics (ADAHELI) is a Small Mission to
study the structure and fast dynamics of the low solar atmosphere,
performing Visible-NIR monochromatic and broad-band observations. The
mission will achieve millimeter full disk observations as well. The
ADAHELI Team has succesfully completed, in December 2008, the Phase
A study awarded by the Italian Space Agency (ASI). The Interferometer
for SOlar Dynamics (ISODY), on board the ADAHELI satellite, comprises
a Gregorian telescope and its focal plane suite. The advanced design
focal plane suite uses fast CMOS cameras for investigating photospheric
and chromospheric fast dynamics and structure. ISODY is equipped
with a pioneering focal plane suite composed of a spectral channel,
based upon a tandem of Fabry-Perot interferometers operating in the
visible-NIR spectral region, a broad band channel for high resolution
imaging, and a correlation tracker used as an image stabilization
system. ADAHELI's mission profile has been tailored to limit the
spacecraft's radial velocity in the Sunward direction, to not exceed
+/-4 km/s, during 95% of the yearly orbit, to allow a continuous use
of the on-board interferometer.
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Title: Imaging performance of multi-etalon bidimensional spectrometers
Authors: Righini, A.; Cavallini, F.; Reardon, K. P.
2010A&A...515A..85R Altcode:
<BR /> Aims: In recent years, several new solar and nighttime
panoramic spectrometers based on Fabry-Perot interferometers have
been successfully developed. In this paper we evaluate the imaging
performance of the two types of mountings that have been adopted,
telecentric and classic, in particular trying to understand which one
might be more suitable for future large-aperture solar telescopes. <BR
/> Methods: Numerical code was written to simulate the behavior of such
spectrometers, on the basis of the theory of Fourier optics. This code
was used to simulate different instrument configurations and was tested
on previous results obtained either analytically or numerically by
other authors. <BR /> Results: Calculations of the system MTF and Strehl
ratios show that both mountings may perform very close to theoretical
expectations. However, gap irregularities in the interferometers
may alter the optical quality of the monochromatic images. In the
case of the classical mounting in a collimated beam, it is possible
to partially compensate for the resulting errors in the wavefront
emerging from the interferometers with a suitable phase plate. We also
performed an observational test of the optical quality delivered by
the IBIS interferometer installed at the Dunn Solar Telescope of the
National Solar Observatory, with the results substantially confirming
the calculations. <BR /> Conclusions: It follows from our results
that both mountings may be efficiently used for solar bidimensional
spectroscopy. The final choice depends on the tradeoff between factors
such as image quality, field of view, and acceptable wavelength shift.
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Title: The ADAHELI solar mission: Investigating the structure of
Sun's lower atmosphere
Authors: Berrilli, F.; Bigazzi, A.; Roselli, L.; Sabatini, P.; Velli,
M.; Alimenti, F.; Cavallini, F.; Greco, V.; Moretti, P. F.; Orsini,
S.; Romoli, M.; White, S. M.; ADAHELI Team; Ascani, L.; Carbone, V.;
Curti, F.; Consolini, G.; Di Mauro, M. P.; Del Moro, D.; Egidi, A.;
Ermolli, I.; Giordano, S.; Pastena, M.; Pulcino, V.; Pietropaolo, E.;
Romano, P.; Ventura, P.; Cauzzi, G.; Valdettaro, L.; Zuccarello, F.;
ADAHELI Team
2010AdSpR..45.1191B Altcode: 2010AdSpR..45.1191A
ADAHELI (ADvanced Astronomy for HELIophysics) is a small-class
(500 kg) low-budget (50 MEuro) satellite mission for the study of
the solar photosphere and the chromosphere and for monitoring solar
flare emission. ADAHELI's design has completed its Phase-A feasibility
study in December 2008, in the framework of ASI's (Agenzia Spaziale
Italiana) 2007 "Small Missions" Program (calling for two missions at
50 MEeuros each, plus the launch budget). ADAHELI's main purpose is
to explore Sun's lower atmosphere in the near-infrared, a region so
far unexplored by solar observations from space. ADAHELI will carry
out observations of the solar photosphere and of the chromosphere at
high-temporal rate and high spatial and spectral resolutions. ADAHELI
will contribute to the understanding of Space Weather through the
study of particle acceleration during flares. A radiometer operating
in the millimeter radio band will continuously monitor the solar disk,
throughout the spacecraft's life time. ADAHELI's baseline instruments
are a 50-cm high-resolution telescope operating in the visible and
the near-infrared, and a lightweight full-disk radiometer operating at
millimeter wavelengths (90 GHz). The core of the telescope's focal plane
suite is the spectral imager based on two Fabry-Perot interferometers,
flying for the first time on a solar mission. The instrument
will return fast-cadence, full bi-dimensional spectral images at
high-resolution, thus improving on current slit-scan, mono-dimensional
architectures. Moreover, the possibility of working in polarized light
will enable full 3D magnetic field reconstruction on the photosphere
and the chromosphere. An optional instrumental package is also being
proposed to further extend ADAHELI's scope: a full-disk telescope for
helioseismology based on a double Magneto-Optical Filter, a Neutral
Particle Analyzer for magnetospheric research, an Extreme Ultraviolet
imaging and spectro-radiometry instrument. These options fall outside
the prescribed budget. ADAHELI, flying a Sun-Synchronous orbit at 800
km, will perform continuous, long-duration (4-h), daily acquisitions,
with the possibility of extending them up to 24 h. ADAHELI's operating
life is two years, plus one extension year. Launch would be nominally
planned for 2014.
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Title: The ADAHELI Solar Mission
Authors: Berrilli, F.; Velli, M.; Roselli, L.; Bigazzi, A.; Moretti,
P. F.; Romoli, M.; Orsini, S.; Cavallini, F.; Greco, V.; Carbone,
V.; Consolini, G.; Di Mauro, M. P.; Ermolli, I.; Pietropaolo, E.;
Romano, P.; Ventura, P.; White, S. M.; Zuccarello, F.; Cauzzi, G.;
Valdettaro, L.
2008ESPM...12..6.6B Altcode:
ADAHELI (Advanced Astronomy for HELIOphysics) is an Italian Space
project for the investigation of solar photospheric and chromospheric
dynamics, via high-resolution spectro-polarimetric observations in the
near-infrared spectral range. The mission has been financed for phase
A study in the framework of ASI Italian Space Agency Small Missions
Program call of September 2007. <P />Four fields have been selected
to highlight the specific benefits of ADAHELI scientific payload: 1)
Photospheric and chromospheric dynamics and structure, 2) Emergence and
evolution of solar active regions and solar irradiance, 3) Chromospheric
and corona heating and turbulence, 4) Solar flares in the millimeter
wavelength region. <P />The principal science instrument, ISODY, is
a 50 cm solar telescope equipped with an innovative Focal Plane Suite
composed of a spectro-polarimetric imager, based upon two Fabry-Perot
interferometers operating in the NIR regions around 845nm and 1083nm, a
broad band imager, and a correlation tracker used as image stabilization
system. <P />Designed Mission Profiles for ADAHELI intend to achieve
continuous high-spectral and spatial resolution observations of the
Sun for a routine duration of 4 hours with a goal to be extended to
24 hours. <P />ADAHELI also carries MIOS, a millimeter wavelengths
radiometer operating at around 90 GHz for flare detection. <P />The
ADAHELI payload's instrument suite integrates and complements, without
overlap, the present major objectives of ESA, NASA and the International
Living with a Star program, in particular Solar Dynamics Observatory,
PICARD, Solar Orbiter, and the Solar Probe missions. <P />Proposals
for optional instruments are also under evaluation: DIMMI-2h, a
double channel MOF based full disk imager operating at 589nm and
770nm, allowing high temporal resolution velocity and magnetic field
measurements; EISR a two channel spectrometer operating in the 50-130
nm wavelength range, and NPA, an in-situ Neutral Particle Analyzer
to detect Energetic Neutral Atoms (ENA). Science objectives related
to optional instruments include: solar high and low-degree p modes
oscillations, EUV solar structures and variability, solar gravitational
red-shift measurement, detection of ENA originating from the plasma
region in the Earth's magnetosphere and undergoing reflection from
the Earth's atmosphere.
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Title: Characterization of Fabry-Perot interferometers and
multi-etalon transmission profiles. The IBIS instrumental profile
Authors: Reardon, K. P.; Cavallini, F.
2008A&A...481..897R Altcode:
Aims: Properly characterizing Fabry-Perot interferometers (FPI) is
essential for determining their effective properties and evaluating
the performance of the astronomical instruments in which they are
employed. Furthermore, in two-dimensional spectrographs where multiple
FPI are used in series, the actual distribution of plate separation
errors will be crucial for determining the resulting transmission
profiles. We describe techniques that address these issues utilizing
the FPI of IBIS, a solar bidimensional spectrometer installed at the
Dunn Solar Telescope. <BR />Methods: A frequency-stabilized He-Ne
laser was used in three different optical layouts to measure the
spatially-resolved transmission of the FPI. Analyzing the shape and
wavelength shift of the observed profiles allows the characteristics of
the cavity errors and the interferometer coating to be determined. <BR
/>Results: We have measured the spatial distribution of the large-scale
plate defects, which shows a steep radial trend, as well as the
magnitude of the small-scale microroughness. We also extracted
the effective reflectivity and absorption of the coating at the
laser line wavelength for both interferometers. <BR />Conclusions:
These techniques, which are generally applicable to any Fabry-Perot
interferometer, provide the necessary information for calculating
the overall instrumental profile for any illuminated area of the
interferometer plates. Accurate knowledge of the spectral transmission
profile is important, in particular when using inversion techniques
or in comparing observations with simulated data.
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Title: The solar chromosphere at high resolution with IBIS. I. New
insights from the Ca II 854.2 nm line
Authors: Cauzzi, G.; Reardon, K. P.; Uitenbroek, H.; Cavallini, F.;
Falchi, A.; Falciani, R.; Janssen, K.; Rimmele, T.; Vecchio, A.;
Wöger, F.
2008A&A...480..515C Altcode: 2007arXiv0709.2417C
Context: The chromosphere remains a poorly understood part of the solar
atmosphere, as current modeling and observing capabilities are still
ill-suited to investigating its fully 3-dimensional nature in depth. In
particular, chromospheric observations that can preserve high spatial
and temporal resolution while providing spectral information over
extended fields of view are still very scarce. <BR />Aims: In this
paper, we seek to establish the suitability of imaging spectroscopy
performed in the Ca II 854.2 nm line as a means of investigating
the solar chromosphere at high resolution. <BR />Methods: We utilize
monochromatic images obtained with the Interferometric BIdimensional
Spectrometer (IBIS) at multiple wavelengths within the Ca II 854.2 nm
line and over several quiet areas. We analyze both the morphological
properties derived from narrow-band monochromatic images and the
average spectral properties of distinct solar features such as network
points, internetwork areas, and fibrils. <BR />Results: The spectral
properties derived over quiet-Sun targets are in full agreement with
earlier results obtained with fixed-slit spectrographic observations,
highlighting the reliability of the spectral information obtained
with IBIS. Furthermore, the very narrowband IBIS imaging reveals very
clearly the dual nature of the Ca II 854.2 nm line. Its outer wings
gradually sample the solar photosphere, while the core is a purely
chromospheric indicator. The latter displays a wealth of fine structures
including bright points akin to the Ca II H{2V} and K{2V} grains, and
as fibrils originating from even the smallest magnetic elements. The
fibrils occupy a large fraction of the observed field of view, even
in the quiet regions, and clearly outline atmospheric volumes with
different dynamical properties, strongly dependent on the local magnetic
topology. This highlights how 1D models stratified along the vertical
direction can provide only a very limited representation of the actual
chromospheric physics. <BR />Conclusions: Imaging spectroscopy in the
Ca II 854.2 nm line currently represents one of the best observational
tools for investigating the highly structured and highly dynamical
chromospheric environment. A high-performance instrument such as IBIS
is crucial in achieving the necessary spectral purity and stability,
spatial resolution, and temporal cadence. <P />Two movies are only
available in electronic form at http://www.aanda.org
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Title: IBIS: A New Post-Focus Instrument for Solar Imaging
Spectroscopy
Authors: Cavallini, F.
2006SoPh..236..415C Altcode:
A new instrument for solar bi-dimensional spectroscopy, the
Interferometric BIdimensional Spectrometer (IBIS), has been successfully
installed at the Dunn Solar Telescope of the National Solar Observatory
(USA-NM) in June 2003. This instrument is essentially composed of a
series of two Fabry-Perot interferometers and a set of narrow-band
interference filters, used in a classic mount and in axial-mode. It
has been designed to take monochromatic images of the solar surface
with high spectral (R ≥ 200 000), spatial ≃ 0.2″), and temporal
resolution (several frames s<SUP>−1</SUP>). IBIS has a circular field
of view, 80″ in diameter and, with suitable interference filters,
it can be used in the wavelength range 580 - 860 nm. The wavelength
stability of the instrumental profile is very high, the maximum
drift in 10 hours amounting to ≃10 m s<SUP>−1</SUP>. In this
paper the criteria used in the design and the expected instrumental
characteristics are described.
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Title: The Interferometric Bidimensional Spectrometer (IBIS)
Authors: Cauzzi, Gianna; Cavallini, F.; Reardon, K.; Berrilli, F.;
Rimmele, T.; IBIS Team
2006SPD....37.0608C Altcode: 2006BAAS...38..226C
The Interferometric Bidimensional Spectrometer (IBIS) is an advanced
instrument for imaging spectroscopy installed at the Dunn Solar
Telescope at NSO/Sacramento Peak. The instrument has been constructed by
a consortium of italian institutes and allows for observations of the
photosphere and chromosphere at high spatial, spectral, and temporal
resolution. Such observations are essential for performing spatial
and spectral comparisons with numerical simulations. We will present
some of the performance characteristics of the instrument and show some
examples of the IBIS data. We will also show some initial results of the
recently tested polarimetric mode. IBIS is available for community use
as a facility instrument of NSO.IBIS has been funded by the Italian
Research Ministry (MIUR), the Italian Institute for Astrophysics
(INAF), and the Universities of Florence and Rome. Additional support
is provided by the National Solar Observatory.
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Title: High Resolution Spectropolarimetry of Penumbral Formation
with IBIS
Authors: Reardon, Kevin; Casini, R.; Cavallini, F.; Tomczyk, S.;
Rouppe van der Voort, L.; Van Noort, M.; Woeger, F.; Socas Navarro,
H.; IBIS Team
2006SPD....37.3503R Altcode: 2006BAAS...38..260R
We present the results of first spectropolarimetric observations
made with the Interferometric Bidimensional Spectrometer (IBIS)
at the NSO/Dunn Solar Telescope. The use of narrowband imaging and
post-facto reconstruction techniques allows for observations close
to the diffraction limit of the vector magnetic field. We will show
observations of the the formation of an individual penumbral filament
around a small pore. We measure the magnetic field and velocity field
of the forming penumbral filament. The spectropolarimetric mode of
IBIS will be available to the community in the fall of 2006.
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Title: IBIS instrumental characteristics and first results
Authors: Cavallini, F.; Reardon, K.
2006MSAIS...9...55C Altcode:
The Interferometric BIdimensional Spectrometer (IBIS) was installed in
June 2003 at the DST/NSO, where it is used in conjuction with a high
order AO system. IBIS has since proved to be a reliable and versatile
instrument for performing high resolution observations in both the
photosphere and chromosphere. We describe here the instrument and its
performance characteristics especially with respect to the obtainable
spectral, temporal and spatial resolutions, providing examples of the
actual observations.
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Title: IBIS: Instrument Description and First Results
Authors: Cavallini, F.; IBIS Team
2004AAS...204.3709C Altcode: 2004BAAS...36R.710C
In June 2003, the Inferometric Bidimensional Spectrometer (IBIS)
was installed at the Dunn Solar Telescope at Sacramento Peak
Observatory. This new instrument uses two Fabry-Perot interferometers to
permit the detailed sampling (30-40 mÅ FWHM) of solar spectral lines
over an 80 arcsecond diameter field of view in the range 5800-8600
Å. IBIS operates in combination with the NSO adaptive optics system,
allowing it to achieve diffraction-limited images, while being able to
scan through an entire spectral line in 5-10 seconds. The instrument
design placed a premium on reducing parasitic spectral light and
maintaining a stable and uniform spectral transmission profile across
the field of view. <P />We present the operational characteristics
of the instrument as determined from laboratory calibrations as
well as tests performed during the initial observing runs with the
instrument. We provide examples of the datasets obtained during these
first observing runs and some preliminary results gleaned from these
data. We also indicate some of the scientific programs for which this
instrument is ideally suited.
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Title: IBIS Observations of Quiet Sun Photosphere - Velocity Structure
from Fe I 7090.4 Å
Authors: Janßen, Katja; Cauzzi, Gianna; Falchi, Ambretta; Cavallini,
Fabio; Reardon, Kevin
2004IAUS..223..631J Altcode: 2005IAUS..223..631J
In our contribution we introduce the new Interferometric BIdimensional
Spectrometer (IBIS) and present the first results on bisector velocities
of two dimensional spectral scans in FeI 7090.4 Å comparing granules
and intergranular regions.
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Title: Recent results from IBIS
Authors: Cavallini, F.; Baffa, C.; Reardon, K.; Berrilli, F.;
Cantarano, S.; Egidi, A.
2003MmSAI..74..796C Altcode:
IBIS (Interferometric BIdimensional Spectrometer) is a new instrument
for solar bidimensional spectroscopy. It essentially consists
of two Fabry-Perot interferometers, piezo-scanned and capacity
servo-controlled, used in classic mount and in axial-mode, in series
with a set of narrow-band interference filters. This instrument will
operate on a large field of view (80") and on a large wavelength
range (580 - 860 nm), with high spectral, spatial and temporal
resolution. IBIS, developed to become one of the focal plane instruments
of THEMIS, has been completed in its essential form and some tests have
been already performed. It is now possible therefore to compare expected
with measured values of the more relevant instrumental parameters.
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Title: Characterization of the IBIS Transmission Profile
Authors: Reardon, K.; Cavallini, F.
2003MmSAI..74..815R Altcode:
We describe the techniques used to characterize the components of
the IBIS instrument in the laboratory in order to determine the
operational performance of the completed instrument. In particular,
we have measured the surface and coating irregularities of the two
Fabry-Perot interferometers at the heart of IBIS. From this we construct
a theoretical transmission profile for the instrument and relate that
to the accuracy that can be obtained in measurements of the Sun.
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Title: IBIS (Interferometric BIdimensional Spectrometer)
Authors: Cavallini, F.
2002ESASP.477..585C Altcode: 2002scsw.conf..585C
IBIS is a new instrument for solar bidimensional spectroscopy, now under
construction at the Arcetri Astrophysical Observatory. It essentially
consists in two Fabry-Perot interferometers, used in classic mount
and in axial mode, in series with a set of narrow-band interference
filters. This instrument will operate on a large wavelength range,
with high spectral, spatial and temporal resolution. Some preliminary
results, obtained during the ongoing evaluation of the instrumental
set-up will be described.
---------------------------------------------------------
Title: IBIS: a new instrument for solar bidimensional spectroscopy
Authors: Cavallini, F.; Berrilli, F.; Cantarano, S.; Egidi, A.
2001MmSAI..72..554C Altcode:
IBIS is a new instrument for solar bidimensional spectroscopy, now
under construction in Arcetri, which will operate on a large field
of view and on a large wavelength range, with high spectral, spatial
and temporal resolution. When completed in 2002, it will be one of the
leading instruments for solar research, well suited for new generation
telescopes such as THEMIS.
---------------------------------------------------------
Title: IBIS: A Purely Interferometric Instrument for Solar
Bidimensional Spectroscopy
Authors: Cavallini, F.; Berrilli, F.; Cantarano, S.; Egidi, A.
2000ESASP.463..607C Altcode: 2000sctc.proc..607C
No abstract at ADS
---------------------------------------------------------
Title: Italian panoramic monochromator for the THEMIS telescope:
the first results and instrument evaluation
Authors: Cavallini, Fabio; Berrilli, Francesco; Caccin, Bruno;
Cantarano, Sergio; Ceppatelli, Guido; Egidi, Alberto; Righini, Alberto
1998SPIE.3355..940C Altcode:
We briefly describe the design and the characteristics of the Italian
Panoramic Monochromator installed at the focal plane of the THEMIS
telescope built in Izana by a joint venture of the French and Italian
National Research Councils. The Panoramic Monochromator substantially
is a narrow band filter (approximately equals 22 mAngstrom bandwidth)
tunable on the visible spectrum for quasi simultaneous bidimensional
spectrometry of the solar atmosphere. The narrow bandwidth is
obtained by using a non standard birefringent filter and a Fabry Perot
interferometer mounted in series. This assembly has the advantage of
the spectral purity of one channel of the Fabry Perot interferometer
and a very large free spectral range. Moreover the spectral stability
depends on the interferometer, the environment of which may be carefully
controlled. The design of this instrument is not really new, but,
only now it has been possible to build it thanks to the development
of servo controlled Fabry Perot interferometers, which are stable in
time and may easily be tuned. The system seems to perform well. It is
stable in wavelength and the spectral pass band and stray light are
within the expected values, as it may be deduced by very preliminary
tests performed at the THEMIS Telescope and in Arcetri (Firenze) at the
'G. B. Donati' solar tower.
---------------------------------------------------------
Title: The Italian Panoramic Monochromator
Authors: Cavallini, F.
1998A&AS..128..589C Altcode:
A new instrument for solar bidimensional spectroscopy, the Italian
Panoramic Monochromator (IPM), has been recently installed on the
Telescope Heliographique pour l'Etude du Magnetisme et des Instabilites
de l'atmosphere Solaire (THEMIS), the French-Italian solar telescope
built in Tenerife (Canary Islands). On a square field 33”x 33”,
this instrument allows one to obtain monochromatic images of the solar
surface with high spectral resolution ({cal R} >= 256000 at 5500
Angstroms), preserving all the spatial resolution delivered by the
telescope ( =~ 0.2”). The wavelength stability of the instrumental
profile is very high, the maximum drift in 10 hours amounting to about
10 ms(-1) .
---------------------------------------------------------
Title: Purely interferometric solar bidimensional spectroscopy
Authors: Cavallini, F.
1998MmSAI..69..627C Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The IPM-Italian Panoramic Monochromator operating at the
THEMIS telescope.
Authors: Cavallini, F.; Ceppatelli, G.; Righini, A.; Berrilli, F.;
Caccin, B.; Cantarano, S.; Egidi, A.
1997cpyt.conf..119C Altcode:
From April 20, 1997 the Italian Panoramic Monochromator (henceforth IPM)
will be the first operating mode of the THEMIS telescope. It basically
consists of a Fabry-Perot interferometer mounted in tandem with an
universal birefringent filter. The image acquisition system consists
of two CCD cameras controlled and read-out by dedicated electronics and
personal computers. One of these cameras acquires a simultaneous white
light image for the application of off-line destretching procedures
in order to reduce seeing effects. An optical link connects the CCD
camera and the PCs while the handshaking and the data transfer between
the PCs and the work station controlling the IPM is performed via LAN
and IEE488 bus.
---------------------------------------------------------
Title: A rheological model for anelastic anisotropic media with
applications to seismic wave propagation
Authors: Carcione, José M.; Cavallini, Fabio
1994GeoJI.119..338C Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The height dependence of intensity and velocity structures
in the solar photosphere
Authors: Salucci, G.; Bertello, L.; Cavallini, F.; Ceppatelli, G.;
Righini, A.
1994A&A...285..322S Altcode:
Results about a statistical analysis of the solar granulation, obtained
by analyzing a series of narrow band (20 mA FWHM) images in the 6162.18
A CaI photospheric line, are presented. The observations have been
performed at the Vacuum Solar Tower of the National Solar Observatory
at Sac. Peak (NM-USA) in 1988, using a Fabry-Perot interferometer and a
Universal Birefringent Filter mounted in tandem. We computed coherence,
phase and power spectra of intensity and velocity fields in a 27"x27"
quiet region at the disk center. Energy spectra, plotted in the usual
log-log coordinates, clearly show a linear shape for wavenumbers between
3 and 10 Mm^-1^. The exponent is -17/3: it does not significatively vary
within the considered photospheric layers and largely differs from both
the theoretical value and the results of previous 1-D observations. This
result indicates that in the photosphere we are in presence of a
redistribution of the convective energy through a cascade from larger
granules to smaller ones, although the size distribution does not follow
the Kolmogorov law. The physical processes involved in the granulation
have been investigated by studying the height dependence of coherence
and phase spectra of Velocity-Velocity (V-V) and Velocity-Intensity
(V-I) fields. We find that the photosphere is divided in two regions:
the velocity structures existing in the lower layers (first region)
are convective and extend up to about 170 km. The decay of these
granular motions generates well correlated velocity structures in the
second region (height range 170-400 km), at spatial frequencies 5-10
Mm^-1^. In this region, moreover, the coherence moderately increases
with height, while the phase is stable around +/-180°. This means
that velocity and intensity fields are predominantly anticorrelated,
as expected for gravity waves.
---------------------------------------------------------
Title: The THEMIS telescope
Authors: Rayrole, J.; Mein, P.; Cavallini, F.
1994ASIC..433..507R Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The influence of the stray light in the solar image on the
Fraunhofer line profiles
Authors: Barducci, A.; Cavallini, F.; Ceppatelli, G.; Righini, A.
1994A&A...281..955B Altcode:
In the solar spectroscopy the scattered light produced by the Earth's
atmosphere and telescope optics may bias the result of spectral
and photometric measurements. The problem of correcting the spectral
observations from the stray light has assumed a great importance in the
studies of large-scale motion into the solar atmosphere. Nevertheless,
it is not yet known how the light smearing may affect the observed
values of the relevant parameters of the Fraunhofer lines, with the
exception of their wavelengths (the so called 'velocity error') which
has been already examined. In this paper we discuss the effects of the
light scattering in the solar image on the spectroscopic measurements
and we discuss some data reduction techniques. Moreover we calculate
the analytical distribution of the velocity error over the solar disk,
obtaining new insights on the understanding of the solar rotation
peculiarities.
---------------------------------------------------------
Title: Project for the installation of the panoramic monochromator
to the THEMIS solar telescope
Authors: Cavallini, F.
1993MmSAI..64..764C Altcode:
No abstract at ADS
---------------------------------------------------------
Title: First measurements of solar oscillations with the THEMIS
panoramic monochromator
Authors: Berrilli, F.; Caccin, B.; Cantrano, S.; Cavallini, F.;
Ceppatelli, G.; Egidi, A.; Francia, P.; Pietropaolo, E.; Righini, A.
1993MmSAI..64..781B Altcode:
No abstract at ADS
---------------------------------------------------------
Title: High-resolution spectroscopic imaging of the Sun with a
Universal Birefringent filter and a Fabry-Perot interferometer.
Authors: Cavallini, F.; Ceppatelli, G.; Righini, A.; Berrilli, F.;
Caccin, B.; Cantarano, S.; Egidi, A.; Francia, P.; Pietropaolo, E.
1992NCimC..15..509C Altcode:
The authors describe an optical device consisting of a Universal
Birefringent Filter and a Fabry-Perot interferometer used in tandem
to obtain monochromatic images of the Sun in the visible spectrum
(between 4200 and 7000 Å). They give an account of the preliminary
results obtained by measuring the global velocity field on the solar
photosphere. These results show that the instrument is well suited
for global oscillation measurements.
---------------------------------------------------------
Title: High resolution granulation spectrophotometry with a UBF and
a FP interferometer in tandem.
Authors: Salucci, G.; Bertello, L.; Righini, A.; Bonaccini, D.;
Cavallini, F.; Ceppatelli, G.
1992ESASP.344..157S Altcode: 1992spai.rept..157S
Recent studies have shown that in the solar granulation, granules sizes
lower than 3″may be considered as turbulent eddies. However this
result is in contradiction with morphological studies carried out by
other authors. In this paper the authors analyse in the spatial domain
the autocorrelation and crosscorrelation functions of the velocity
and of the intensity fields at several depths in the solar atmosphere,
using narrow band filtergrams obtained at Sacramento Peak Observatory
Vacuum Tower Telescope with a UBF and a FP interferometer mounted in
tandem. The results show that the granular motion is turbulent for
heights larger than 170 km while at lower heights is convective.
---------------------------------------------------------
Title: About Spectroscopic Measurements of the Solar Meridional Motion
Authors: Cavallini, F.; Ceppatelli, G.; Righini, A.
1992A&A...254..381C Altcode:
A large number of spectroscopic measurements of meridional mass
motion on the Sun has been carried out in the past. The results are
rather contradictory, although a 10 ms<SUP>-1</SUP> poleward flow
might be inferred. Some authors have pointed out that the so called
"meridional motion" might be ascribed to a latitudinal dependence of
the convective flux. In this paper we describe new observations carried
out with the spectro-interferometer installed at the G.B. Donati Solar
Tower in Arcetri: these measurements have been performed using lines
having either similar or very different physical parameters in order
to disentangle convective effects from true mass flows. We discuss the
results and we conclude that the great variety of "meridional motions"
so far observed by spectroscopic means may be ascribed to an intrinsic
variability of the meridional flow pattern and in part to the presence
of a large scale velocity field.
---------------------------------------------------------
Title: The solar aureola - Theory and observations
Authors: Barducci, A.; Righini, A.; Cavallini, F.; Ceppatelli, G.
1990A&A...240..203B Altcode:
The stray light, which originates in the earth atmosphere and in the
telescope optics, produces a 'cross-talk' between spectral as well
as intensity information held in different picture elements. In this
paper the mathematical formulation of the scattering processes and
their dependence on the wavelength and on the zenith distance of the
source are discussed and compared with aureola observations carrried
out at the G.B. Donati Solar Tower in Arcetri. The analysis confirms
the zenith and wavelength dependence of the relevant aureola parameters
as given by the theory, and shows that the logarithmic description
of the aureola intensity, sometime given by other authors, correctly
applies also to the Arcetri measurements. This result suggests the
possibility of evaluating the stray light effects on spectroscopic
and photometric observations stemming from a few aureola measurements
performed at given distances from the solar limb.
---------------------------------------------------------
Title: Depth dependence of the intensity-velocity phase difference
in the solar '5-min' oscillations
Authors: Alamanni, N.; Bertello, L.; Righini, A.; Cavallini, F.;
Ceppatelli, G.
1990A&A...231..518A Altcode:
Previous measurements carried out on four Fe I photospheric lines have
suggested that the different oscillating power observed on the blue and
red line flanks is produced by the intensity-velocity phase lag in the
'5-min' waves. Former measurements and new additional observations on
the 6149.2 A Fe II and 6162.2 A Ca I lines have been used to evaluate
more accurately the dependence of this intensity-velocity phase
difference on the photospheric height. A nonadiabatic and nonisothermal
bidimensional model of the thermodynamic fluctuations induced in the
photosphere by the high degree p-modes suggests that radiative damping
might explain the observed line profile oscillations.
---------------------------------------------------------
Title: CA I 6162 A line oscillations observed in a solar active region
Authors: Alamanni, N.; Righini, A.; Cavallini, F.; Ceppatelli, G.
1990A&A...228..517A Altcode:
The effect of the magnetic field on the high degree p-modes in the
solar atmosphere is still controversial, both from the theoretical
and the experimental point of view. The temporal behavior of the 6162
A Ca I line profile in an active region has been observed with the
spectrointerferometer of the Arcetri solar tower. It is found that
the presence of magnetic field suppresses several modes of oscillation
and that the line oscillates almost 'rigidly'.
---------------------------------------------------------
Title: High resolution solar bidimensional spectroscopy with
a universal birefringent filter in tandem with a Fabry-Perot
interferometer
Authors: Bonaccini, D.; Righini, A.; Cavallini, F.; Ceppatelli, G.
1989A&A...217..368B Altcode:
The design of an optical device consisting of a universal birefringent
filter and a Fabry-Perot interferometer to obtain monochromatic images
of the solar atmosphere with a spectral resolving power of about 300,000
is discussed. The instrument may be continuously tuned between 4200 A
and 7000 A and, using commercially available Fabry-Perot, may reach a
wavelength stability of about 0.1 mA. This system preserves all the
spatial resolution delivered by the telescope and limits the size
of the observable field to a maximum of 400 widths of the telescope
diffraction pattern.
---------------------------------------------------------
Title: Polarization properties of a `Zeiss-type' coelostat: The case
of the solar tower in Arcetri
Authors: Capitani, C.; Landi Degl'Innocenti, E.; Cavallini, F.;
Ceppatelli, G.; Landi Degl'Innocenti, M.; Landolfi, M.; Righini, A.
1989SoPh..120..173C Altcode:
A theoretical model of the polarization properties of a `Zeiss-type'
coelostat is presented and discussed in detail. The Muller matrix
describing the modification of the Stokes vector of the incident
radiation as a result of the multiple reflections on the coelostat
mirrors is derived as a function of the solar coordinates, the
geometrical configuration of the coelostat, and the parameters defining
the optical properties of the mirrors. These parameters, or more
particularly, the index of refraction n and the extinction coefficient
k, have been evaluated by means of laboratory measurements performed
on a series of specimens having characteristics similar to those of
the coelostat mirrors. The geometry of the coelostat configuration
is described in full detail. The theoretical model has been then
particularized to the case of the Donati Solar Tower in Arcetri,
and some experimental measurements have been performed to check the
correctness of the model. These measurements show the basic adequacy
of the mathematical model, although some offset terms are found in
the Stokes parameters U and V.
---------------------------------------------------------
Title: Line Bisectors In and Out Magnetic Regions
Authors: Cavallini, F.; Ceppatelli, G.; Righini, A.
1989ASIC..263..283C Altcode: 1989ssg..conf..283C
No abstract at ADS
---------------------------------------------------------
Title: Profile variations of some photospheric lines as observed in
active regions across the solar disk
Authors: Cavallini, F.; Ceppatelli, G.; Righini, A.
1988A&A...205..278C Altcode:
Some photospheric lines have been observed in active regions at
different distances from the solar disk center. Assuming that the
line weakening monotonically changes with the changing of the magnetic
field intensity, it is established for the observed lines how the line
width, line asymmetry and line shift vary with the magnetic field. In
particular, near the disk center, an increasing red-shift of the higher
part of the lines is observed with the increasing of the field, while,
at the bottom of a strong line, a small blue-shift is observed. These
results may be interpreted as due to the fading of the convection in
active regions produced by the magnetic field.
---------------------------------------------------------
Title: Bounds on the eigenvalues of the planetary-scale baroclinic
instability problem
Authors: Cavallini, Fabio; Crisciani, Fulvio; Mosetti, Renzo
1988DyAtO..12...71C Altcode:
In the framework of the linear baroclinic instability problem for
planetary geostrophic flows, bounds on the related complex eigenvalues
are deduced. The main feature of this result is the independence
of these bounds from the latitude and the density stratification,
so that it generalizes the results of previous work on the subject.
---------------------------------------------------------
Title: The spectro-interferometer of the Arcetri Solar Tower
Authors: Cavallini, F.; Ceppatelli, G.; Meco, M.; Paloschi, S.;
Righini, A.
1987A&A...184..386C Altcode:
The authors describe the spectro-interferometer installed at the
Arcetri Observatory Solar Tower. This instrument basically consists
of a Fabry-Perot interferometer mounted in tandem with a medium sized
grating spectrograph, acting as order sorter. This mounting allows
the measurement of solar absorption lines in the range 5500 - 6500
Å with high wavelength stability (0.08 mÅ rms in 12 h) and high
spectral resolution (900,000 at 6328 Å). An image guider allows
the pointing of an assigned solar region with an accuracy better
than 2arcsec rms. This instrument, suitable for investigating line
shifts and asymmetries, has been extensively used for studying such
solar problems as meridional mass motions, line asymmetry "5-min"
oscillations, and convective effects in solar active regions.
---------------------------------------------------------
Title: 5-min oscillations in the wings and bisectors of solar
photospheric Fe I lines
Authors: Cavallini, F.; Ceppateli, G.; Righini, A.; Alamanni, N.
1987A&A...173..161C Altcode:
Former observations carried out at the center of the solar disk on three
Fe I photospheric lines have shown that, during the 5-min oscillation,
the bisector and the line flanks show an oscillation amplitude
decreasing in a different way from the line core to the continuum. New
observations, obtained in a magnetically insensitive line, in and
outside the disk center, confirm the previous findings. From these
and the former measurements it follows that the ratio between the
V<SUB>rms</SUB> of the blue and the red flanks in the observed
lines depends on the height in the photosphere. This result may be
qualitatively interpreted as due to the coupling of the velocity and
brightness oscillations in the 5-min waves, and its height dependence
as due to a phase effect.
---------------------------------------------------------
Title: Interpretation of shifts and asymmetries of Fe I lines in
solar facular areas
Authors: Cavallini, F.; Ceppatelli, G.; Righini, A.
1987A&A...173..155C Altcode:
An attempt is made to evaluate the effect in active regions of
the suppression of convective phenomena, and of the different line
profiles arising from the fluxtubes on the spatially averaged line
profiles. Through use of a multi-column model, the asymmetries and
shifts of three Fe I photospheric lines (g not equal to 0), observed in
facular areas have been analyzed. It is assumed that the facula consists
of magnetic fluxtubes (1.5 kG field) with a zero downflow embedded in
an atmosphere where the convection is partially inhibited. This model
satisfactorily reproduces the observed line shifts and asymmetries
for all three lines.
---------------------------------------------------------
Title: Drift Velocities in Flux Tubes Inferred by Spatially Averaged
Line Bisectors
Authors: Cavallini, F.; Ceppatelli, G.; Righini, A.
1987rfsm.conf..110C Altcode:
The bisectors of the spatially averaged line profiles observed in
active regions may be a useful tool to investigate the drift velocities
within flux tubes. The authors show that a simple heuristic model may
account for the major effects observed in some Fe I line bisectors in
active regions. The model satisfactorily reproduces the behaviour of
the line shifts and asymmetry with the increasing magnetic field. The
authors assume that an active region consists of static magnetic
flux tubes embedded in an atmosphere where the convection is partially
inhibited. However one cannot exclude a slight downflow up to 250 m/s in
the flux tubes. The case of non static flux tubes showing downflows as
large as 1000 - 2000 m/s with disappointing results are also considered.
---------------------------------------------------------
Title: Meridional Flows and Latitudinal Dependence of the Convection
Authors: Cavallini, F.; Ceppatelli, G.; Righini, A.
1987rfsm.conf...21C Altcode:
Theoretical studies on the differential rotation of the Sun require a
surface meridional flow. Recent measurements of the drift of tracers
suggest that this flow must be lower than 1.4 m/s, while spectroscopical
measurements give contradictory results. These measurements may be
strongly affected by different convection between equator and poles
produced by the magnetic field which locally inhibits convective
effects. In the last years several measurements of meridional motion
have been performed at the Arcetri Solar Tower. The authors discuss
from a critical point of view the obtained results.
---------------------------------------------------------
Title: A solar filter for two dimensional spectroscopy
Authors: Bonaccini, Domenico; Righini, A.; Cavallini, F.; Ceppatelli,
G.
1987LIACo..27..235B Altcode: 1987oahp.proc..235B
Not Available.
---------------------------------------------------------
Title: Solar limb effect and meridional flow - Results on the Fe I
lines at 5569.6 A and 5576.1 A
Authors: Cavallini, F.; Ceppatelli, G.; Righini, A.
1986A&A...163..219C Altcode:
A description is given of an investigation on the center-to-limb
variation of the line asymmetry and shift along the polar and equatorial
diameters of the sun on two Fe I photospheric lines. The observations,
obtained with the Fabry-Perot spectrointerferometer installed at the
Donati Solar Tower Telescope in Arcetri, do not show any significant
latitudinal dependence of the line asymmetry. Instead, the limb shift
curves obtained along the polar diameter systematically differ from
those obtained along the equator. This difference, if interpreted as
due to a surface mass flow, implies a poleward meridional motion with
a maximum of about 50 m/s at 45 deg of latitude in both hemispheres. A
detailed analysis of these and previous results suggests that the so
called 'meridional motions', found by spectroscopical means, mainly
originate from latitudinal effects on the convective line shift, which
might also be modulated by the activity cycle. This interpretation does
not exclude the fact that small meridional mass flows are present on
the sun, like those found from the tracers drifts.
---------------------------------------------------------
Title: Long-term width and asymmetry variation of some Fe I
photospheric lines in solar quiet regions at the disk center.
Authors: Cavallini, F.; Ceppatelli, G.; Righini, A.
1986A&A...158..275C Altcode:
Observations obtained in the years 1983 and 1984 at the Donati Solar
Tower in Arcetri show that at the disk center the asymmetry and width
of three Fe I photospheric lines show a long term variation. These
results are in agreement with previous full disk observations of
secular trends in asymmetry and equivalent width.
---------------------------------------------------------
Title: Prospects for an orbital determination and capture cell
experiment
Authors: Cavallini, F.; Ceppatelli, G.; Righini, A.; Alamanni, N.
1986A&A...156..310C Altcode:
Recent measurements of the 7699 Å K I line by other authors have shown
that the line asymmetry, during the 5-min oscillations, varies in an
tiphase with the line shift. We have measured, at the center of the
solar disk, the bisector variations of three Fe I photospheric lines at
6297.8 Å, 6301.5 Å and 6302.5 Å. The oscillating power of the line
bisectors and of the line flanks is distributed in several modes, the
highest one is at 3.45mHz. The power decreases along the bisector from
the line core to the continuum, confirming previous results on the 7699
Å K I line. The oscillating power, at equal intensity levels in all
the three observed lines, is generally different in the two line flanks,
and it decreases differently from the line core to the continuum.
---------------------------------------------------------
Title: Meridional and equatorial center-to-limb variation of the
asymmetry and shift of three Fe I solar photospheric lines around
6300 A
Authors: Cavallini, F.; Ceppatelli, G.; Righini, A.
1985A&A...150..256C Altcode:
In this paper we describe an investigation on the center-to-limb
variation of the line asymmetry and shift along the polar and
equatorial diameters of the Sun, carried out on the Fe I photospheric
lines at 6297.8 Å, 6301.5 Å, and 6302.5 Å. In particular we aim at
ascertaining how much of the so called meridional motion is due to a
possible latitudinal dependence of the convection, and how much to real
large scale mass flows. The observations, obtained with the Fabry-Perot
spectrointerferometer installed at the Donati Solar Tower in Arcetri,
do not show any significant latitudinal effect on the line bisector
shapes. The results regarding the latitudinal dependence of the limb
shift are ambiguous.
---------------------------------------------------------
Title: Shortterm Profile Variations of Photospheric Lines in Solar
Quiet Regions at the Disk Center
Authors: Cavallini, F.; Ceppatelli, G.; Righini, A.
1985tphr.conf...87C Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Terrestrial O2 lines used as wavelength references Experimental
profiles and asymmetries vs. model computations
Authors: Caccin, B.; Cavallini, F.; Ceppatelli, G.; Righini, A.;
Sambuco, A. M.
1985A&A...149..357C Altcode:
In order to evaluate wind and pressure effects on telluric lines,
the profiles and the bisectors of four rotational lines of the
gamma band is compared with the results of detailed theoretical
calculations. The analysis is carried out using standard models of
the terrestrial atmosphere and the molecular data available in the
literature. In particular, a height-dependent pressure shift of the
line profile has been included in the calculations, leading to a
satisfactory agreement with the observations. The computer code for
line transfer in the earth's atmosphere correctly reproduces also the
profiles and the bisectors of the same lines obtained at the height of
the Jungfraujoch, as can be deduced from the Liege Atlas (Delbouille et
al., 1973). Finally, the line shifts observed by Balthasar et al. (1982)
are compared with line shifts computed with the present code, including
wind shifts and pressure shifts. It is found that the amount by which
the varying asymmetry of the lines may affect wavelength determinations
depends upon the definition of the line wavelength itself.
---------------------------------------------------------
Title: Asymmetry and shift of three Fe I photospheric lines in solar
active regions.
Authors: Cavallini, F.; Ceppatelli, G.; Righini, A.
1985A&A...143..116C Altcode:
The asymmetry and the red shift of three Fe I solar lines around 6300 A
have been measured in active regions with a Fabry-Perot spectrometer. At
the disk center, the active region line bisectors are always displaced
to the red and their shape is heavily modified. This red-shift nearly
compensates the convective blue-shift for strong magnetic fields,
suggesting that the inhibition of convection in magnetic regions
might be responsible for the red-shift instead of the often invoked
'downdraft'. Moving from the center to the limb, at about 0.56 solar
radii, the red-shift changes to a slight blue shift. This effect might
explain, without the need of invoking a poleward meridional flow,
why the center to limb red-shift of the line wavelengths is found to
be smaller along the solar equator than along the meridian on large
ensembles of data.
---------------------------------------------------------
Title: Solar Two-Dimensional Spectroscopy with Universal Birefringent
Filters and Fabry-Perot Interferometers
Authors: Bonaccini, D.; Cavallini, F.; Ceppatelli, G.; Righini, A.
1985LNP...233..118B Altcode: 1985hrsp.proc..118B
A bidimensional solar spectrometer that utilizes a Fabry Perot
interferometer (FPI) and a universal birefringent filter (UBF) and
operates in the 4200-7000. A region of the spectrum is described. The
UBF is a chain of nine Lyot elements which are composed of a calcite or
quartz retarder plate, a lambda/4 achromatic wave plate, and an input
and output linear polarizer. The telecentric optical interference
of the system is examined. The high passband wings of the FPI are
analyzed; an FPI in double-pass configuration is proposed to lower
the FPI passband wings and improve its contrast.
---------------------------------------------------------
Title: Short term profile variations of photospheric lines in solar
quiet regions at the disk center.
Authors: Cavallini, F.; Ceppatelli, G.; Righini, A.; Alamanni, N.
1985MPARp.212...87C Altcode:
The authors study short term profile variations of photospheric
lines. These asymmetry oscillations might put new constraints on the
modelling of the line asymmetry forming processes in presence of a
turbulent regimen.
---------------------------------------------------------
Title: Preliminary Results About the Bisector of 6301.5 Solar Line
in Active Regions
Authors: Cavallini, F.; Ceppatelli, G.; Righini, A.
1984ssdp.conf..334C Altcode:
Preliminary results of the observations performed with the Fabry-Perot
spectrometer of the Arcetri Solar Tower show that the bisector of the
6301.5 Fe I solar line is red shifted and the C-shape is distorted in
active regions when compared with that obtained in quiet regions.
---------------------------------------------------------
Title: Absolute measurement of the bisector of the 6301.5091 Fe I
line in the solar spectrum
Authors: Cavallini, F.; Ceppatelli, G.; Righini, A.
1982A&A...109..233C Altcode:
In order to test whether differences in results about the shape of
the 6301.5091 Fe I solar line can be ascribed to temporal fluctuations
of the line asymmetry or to instrumental effects, measurements of the
absolute bisector of the line have been obtained with the Fabry-Perot
interferometer built at the Arcetri Solar Tower. The bisector agrees
with that previously obtained by Adam et al. (1976). The wavelength
of the line coincides with previous measurements, suggesting that, at
the disk center, the line is stable within 5 m/s for an integration
area of two arcmin. This result also shows that the three telluric
lines used as wavelength references are stable down to this limit.
---------------------------------------------------------
Title: Fabry Perot Interferometers for High Resolution Solar
Spectroscopy
Authors: Cavallini, F.; Ceppatelli, G.; Righini, A.
1981siwn.conf..243C Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Solar oscillations
Authors: Cavallini, F.; Ceppatelli, G.; Righini, A.
1980MmSAI..51..611C Altcode:
Theoretical and observational problems in the study of solar
oscillations are reviewed. Consideration is given to models of solar
pulsations, for which accurate values of initial solar abundances
and a more complete knowledge of convective zone dynamics are
required. Measurements of variations in the solar diameter or the
radial velocity of the center of the solar disk are then discussed,
and arguments are presented in favor of the terrestrial origin of the
160-min solar oscillations. The importance of the study of short-period
(about 5 min) solar oscillations to theories of the solar convective
zone is also pointed out.
---------------------------------------------------------
Title: A Fabry Perot spectrometer for measuring solar velocity fields
Authors: Cavallini, F.; Ceppatelli, G.; Barletti, R.; Righini, A.
1980A&A....85..255C Altcode:
A solar spectrometer based on a Fabry-Perot interferometer has been
developed as an alternative to grating spectrometers for measuring solar
velocity fields. The spectrometer features high stability and provides
measurements of velocity fields down to 8 m/s over solar surface areas
up to two arcmin in diameter. Wavelength drifts of the system are slow
and predictable, and the results may be rectified by a continuous test
of the interferometer thickness with a standard wavelength source. Data
obtained on the bisector of the 6301.508 Fe I line are reported.
---------------------------------------------------------
Title: H and K (Ca II) emissions as observed in coronal spectrum in
the July 20, 1963 solar eclipse
Authors: Cavallini, F.; Righini, A.
1975SoPh...45..291C Altcode:
From a detailed analysis of a coronal spectrum taken from a DC-8 jet
airplane during the Eclipse of 20 July, 1963 a rough model of a coronal
cold region (T ≈ 10<SUP>5</SUP> K) has been obtained.
