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Quirrenbach, A., Junkkarinen, V., & Köhler, R. 2003, in ASP Conf. Ser., Vol. 295 Astronomical Data Analysis Software and Systems XII, eds. H. E. Payne, R. I. Jedrzejewski, & R. N.
Hook (San Francisco: ASP), 399
Adaptive Optics Software on the CfAO Web Page
Andreas Quirrenbach, Vesa Junkkarinen, Rainer Köhler
University of California, San Diego, Center for Astrophysics and Space
Sciences, Mail Code 0424, La Jolla, CA 92093-0424, USA
Abstract:
The Center for Adaptive Optics maintains a web site, which serves as a
repository for software and tools related to adaptive optics. We describe the
purpose and structure of this web site, and give brief descriptions of the
currently available software packages. In the future, the CfAO web page can
evolve into a complete data reduction toolbox for adaptive optics observations.
The Center for Adaptive Optics (CfAO) is a Science and Technology Center,
funded by the National Science Foundation. It was established in November 1999
with the mission ``to advance and disseminate the technology of adaptive optics
in service to science, health care, industry, and education''. The activities
of the CfAO cover a broad range of research topics related to adaptive optics;
they also include programs to distribute know-how and tools for adaptive optics
to the scientific community. (One of these programs is an annual summer school
series on adaptive optics for astronomy and vision science.)
Among the goals of the CfAO is the distribution of software for adaptive
optics, with the intention to prevent duplication of efforts by CfAO members
and others, and to give researchers in adaptive optics a place to distribute
their software. One of the CfAO member institutions, the University of
California, San Diego, hosts and maintains a
web server, from which a number of software packages can be downloaded.
The software on this
site comes from the scientists and institutions affiliated with the CfAO, and
from other scientists and institutions interested in sharing AO software with
the astronomical and general scientific community. The philosophy is not to
initiate a coherent software development effort, but rather to gather
independently developed packages, and to make them accessible at one site.
Therefore no attempts have been made to homogenize the programming languages
used, or the platforms on which the programs run. All software packages have
been tested and documented by the respective author(s); in many cases we have
carried out additional testing, and added brief user guides or instructions.
The software and its associated documentation is placed in directories
accessible by anonymous ftp. Web pages provide convenient links to the
directories and/or files for downloading.
The main criterion for the inclusion of software on the CfAO web page has been
their utility for a broad range of users of adaptive optics systems, with a
bias towards packages that CfAO scientists are using for their own research.
The following eight packages are currently available for download from the CfAO
web site:
- A++ This complex package is a tool to generate wavefront
reconstruction matrices for adaptive optics systems, which are used to
calculate the deformable mirror commands from the wavefront sensor data.
A++ was originally written by Walter Wild, and modified by the University of
Chicago AO group. A++ has an extensive user manual. Many astronomical AO
systems with Shack-Hartmann wavefront sensors currently in operation use
versions of Walter Wild's reconstruction matrix.
- AO Simulation Package This software, written by François Rigaut,
simulates an adaptive optics system. The user sets the parameters of the AO
system and telescope. The software calculates the closed-loop performance of
the telescope and AO system and simulates the observation of a star using a
phase screen model for the Earth's atmosphere.
- AOTOOLS This set of scripts written by Eric Steinbring simplifies
the reduction of near-infrared data acquired with an adaptive optics system.
(Most current astronomical AO systems are equipped with near-infrared focal
plane instruments.) The package consists of IRAF cl scripts that need both IRAF
and STSDAS. It installs as an external IRAF package with help files.
- idac This is a large package of software for adaptive optics data
reduction using blind deconvolution. The software has been written and
documented by Stuart Jefferies, Julian Christou, Keith Hege, and Matt Cheselka
(see Jefferies & Christou 1993; Christou et al. 1995). Blind deconvolution is
a technique that allows the point spread function to be determined by the
analysis of multiple images of a single science field, which may or may not
contain point sources. Blind deconvolution has the advantage that many separate
telescope pointings to acquire observations of a calibration point source for
PSF estimation are not required. Blind deconvolution is in many cases
preferable to separate PSF star observations due to the time-variable nature of
the atmosphere and PSF.
- Rainer's Binary/Speckle Package This is a software package written
by Rainer Köhler to reduce speckle data on binary and triple stars (Köhler
et al. 2000). Speckle methods take advantage of short exposures to ``freeze''
the atmospheric seeing, and the binary information is preserved in speckles, or
bright regions. Each image consists of a large number of speckles, and
considerable analysis must be done to extract scientifically useful
measurements from the raw images. The package works completely in the Fourier
domain; it has also been used with great success for adaptive optics
observations of binary stars.
- StarFinder This software package, written by Emiliano Diolaiti and
colleagues at Bologna Observatory, carries out some of the fundamental tasks in
the analysis of adaptive optics data (Diolaiti et al. 2000). It provides both
point spread function estimation and, by using the PSF, astrometry and
photometry in crowded stellar fields. Bright stars are used for an initial
estimate of the point spread function. The PSF estimate and the set of detected
faint stars are then iteratively improved until the entire field is analyzed.
- Strehl Code/FitStars This software, contributed by Theo ten
Brummelaar, is used to analyze an adaptive optics observation of a point source
to estimate the Strehl ratio. The Strehl ratio is the ratio of the peak
intensity actually observed to the peak intensity that would be observed if the
telescope were operating at the diffraction limit. The Strehl ratio is the most
common figure of merit for the performance of an AO system. The package also
contains utilities for photometry, astrometry, and PSF fitting of binary star
images (ten Brummelaar et al. 2000).
- Virtual_Telescope This is an IDL program (with supporting files)
written by Eric Steinbring for the simulation of observations, and to predict
their signal-to-noise ratio. This tool is designed to simulate a telescope
along with its instruments. An artificial field is generated that is deep
enough to test even the capabilities of the James Webb Space Telescope
(JWST). The telescope itself, its point spread function, and backgrounds for
ground or space observations are then simulated.
The first two of these packages ( A++ and the AO Simulation Package)
are primarily meant to be used by designers and operators of adaptive optics
systems. The other packages are more related to observing preparation and data
reduction, and address the needs of astronomers who use AO systems for their
observing projects.
In addition to the software packages described above, the CfAO web page
contains a few introductory articles on adaptive optics, and links to
additional tools that can help to prepare proposals or observing projects. It
is also planned to make a number of test data sets available, which can be used
to investigate the effects of anisoplanatism in reduced images, and to
cross-compare different data reduction and deconvolution algorithms. On a
longer time scale, the CfAO web site could evolve into a complete modular AO
data analysis toolbox (Quirrenbach 1999). This would require contributions from
a larger group of AO users, and a more systematic approach to algorithm
development, interface definitions, coding, and documentation. For the near
future, the main purpose of the CfAO web page will remain the provision
of access to
an increasing number of useful software packages and tools, for anyone
interested in designing or using adaptive optics systems. With this function,
the services provided by the CfAO web page are complementary to those of the
large observatories, which provide complete data reduction pipelines and data
analysis packages, but with no specific emphasis on adaptive optics.
Acknowledgments
We are grateful to all those who have contributed their software and data
reduction tools to our web site. This work has been supported by the National
Science Foundation Science and Technology Center for Adaptive Optics, managed
by the University of California at Santa Cruz under cooperative agreement No. AST-98-76783.
References
Christou, J.C., Hege, E.K., & Jefferies, S.M. 1995, Proc. SPIE
2256, 134
Diolaiti, E., Bedinelli, O., Bonaccini, D., Close, L., Currie, D.,
& Parmeggiani, G. 2000,A&AS, 147, 335
Jefferies, S.M. & Christou, J.C. 1993, ApJ, 415, 862
Köhler, R., Kunkel, M., Leinert, C., & Zinnecker, H. 2000, A&A,
356, 541
Quirrenbach, A. 1999, in Proceedings of ESO/OSA Topical
Meeting on Astronomy with Adaptive Optics, Ed. Bonaccini, D., European Southern
Observatory conference and workshop proceedings, 56, 361
ten Brummelaar, T., Mason, B.D., McAlister, H.A., Roberts, L.C.,
Turner, N.H., Hartkopf, W.I., & Bagnuolo, W.G. 2000, AJ, 119, 2403
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Next: Representations of Spectral Coordinates in FITS
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