Äîêóìåíò âçÿò èç êýøà ïîèñêîâîé ìàøèíû. Àäðåñ îðèãèíàëüíîãî äîêóìåíòà : http://www.stecf.org/conferences/adass/adassVII/reprints/sturme.ps.gz Äàòà èçìåíåíèÿ: Mon Jun 12 18:51:50 2006 Äàòà èíäåêñèðîâàíèÿ: Tue Oct 2 03:10:58 2012 Êîäèðîâêà: Ïîèñêîâûå ñëîâà: zodiacal light

Astronomical Data Analysis Software and Systems VII
ASP Conference Series, Vol. 145, 1998
R. Albrecht, R. N. Hook and H. A. Bushouse, e
Ö Copyright 1998 Astronomical Society of the Pacific. All rights reserved.
ds.
The ISO Spectral Analysis Package ISAP
E. Sturm 1 , O.H. Bauer, D. Lutz, E. Wieprecht and E. Wiezorrek
Max­Planck­Institut fuer extraterrestrische Physik, Postfach 1603,
85740 Garching, Germany
J. Brauer, G. Helou, I. Khan, J. Li, S. Lord, J. Mazzarella, B. Narron
and S.J. Unger
IPAC, California Institute of Technology, MS 100­22, Pasadena, CA
91125, USA
M. Buckley, A. Harwood, S. Sidher and B. Swinyard
Rutherford Appleton Laboratory, Chilton, Didcot, Oxon OX11 0QX, UK
F. Vivares
CESR, BP 4346, 9 av du col. Roche, 31028 Toulouse Cedex, France
L. Verstraete
Institut d'Astrophysique Spatiale, Universite Paris­Sud ­ Bat.121, 91405
Orsay Cedex, France
P.W. Morris
ISO Science Operations Center, P.O. Box 50727, 28080
Villafranca/Madrid, Spain
Abstract. We briefly describe the ISO Spectral Analysis Package ISAP.
This package has been and is being developed to process and analyse data
from the two spectrometers on board ISO, the Infrared Space Observa­
tory of the European Space Agency (ESA). ISAP is written in pure IDL.
Its command line mode as well as the widget based graphical user in­
terface (GUI) are designed to provide ISO observers with a convenient
and powerful tool to cope with data of a very complex character and
structure. ISAP is available via anonymous ftp and is already in use by
a world wide community.
1 Email: sturm@mpe­garching.mpg.de
161

162 Sturm, et al.
1. Introduction
ISO, the Infrared Space Observatory of the European Space Agency, was launched
in November 1995. It carries 4 di#erent instruments including the short and long
wavelength spectrometers SWS and LWS (see Kessler et al. 1996). The ISO
Spectral Analysis Package, ISAP, plays an important role in ISO data analysis.
It is a software package, written in pure IDL 2 , for the reduction and scientific
analysis of the ISO SWS and LWS Auto Analysis Results (AARs). AARs are
the end product of the o#cial automatic pipeline processing, which processes
the raw data, as they are received from the satellite, via a number of interme­
diate products to this AAR stage, which is then sent to the observer. Being
the end product of the pipeline of the spectrometers an AAR should be ­ at
least in principle ­ a ``valid'' spectrum which is appropriate for immediate sci­
entific analysis. However, the spectra are heavily a#ected by glitches, detector
transients, memory e#ects and other phenomena, caused, e.g., by cosmic ray
hits. The best way to cope with these e#ects is to keep as much redundancy as
possible (i.e., all elementary measurements) in the pipeline products, to enable
an appropriate, interactive, post­processing. For this reason elaborate software
has been developed (see e.g., Wieprecht et al. 1998, and Lahuis et al. 1998, for
a description of the SWS pipeline and Interactive Analysis System), and a lot
of instrument and expert knowledge is needed to treat the AARs correctly.
Hence, there was a clear need for a software package that could be given to
the observers in addition to the AARs, to impart the expertise, and to enable the
observers to process the data further and eventually analyse them. Since both
SWS and LWS are spectrometers with AARs that are at least very similar, the
LWS and SWS consortia decided in the summer of 1995 to start a collaboration
to develop such a package as a common tool for both spectrometers.
2. ISAP
A specific emphasis was put on the ability of the computing environment to easily
and immediately plot and visualize data. A widget toolkit was also mandatory.
Since IDL fulfills all the requirements, and since a large part of ISO's data
processing software, like the Interactive Analysis Systems, had already been
written in IDL, it was decided to use it as computing environment for ISAP as
well.
ISAP operates on the final pipeline products, and one of its primary func­
tions is to improve these products (AARs). It therefore o#ers and simplifies
all the necessary steps for post­processing the data. Several functions for data
input and output are available, as well as elaborate plotting tools for visual­
ization. Bad data such as outliers can be masked out, erased or corrected and
replaced. Spectra can, for instance, be averaged, flatfield corrected, normalized,
rebinned and smoothed. Removal of fringes and many more operations can also
be performed.
2 IDL is a trademark of Research Systems Inc. (RSI)

The ISO Spectral Analysis Package ISAP 163
The result of the first part of a typical ISAP session is expected to be a
``simple spectrum'' (single­valued and resampled to uniform wavelength scale
if desired) that can further be analyzed and measured either with other ISAP
functions, native IDL functions, or exported to a di#erent analysis package (e.g.,
IRAF, MIDAS) if desired. ISAP itself provides many tools for detailed analy­
sis, like line and continuum fitting and flux measurements, unit conversions,
conversions from wavelength space to frequency space, dereddening or synthetic
photometry and models including a zodiacal light model to predict and subtract
the dominant foreground at SWS wavelengths.
All these tools and routines are accessible via two di#erent modes: a com­
mand line mode and a Graphical User Interface (GUI). The command line mode
is embedded in the basic IDL environment. Full access to all the ISAP routines
is provided, and, in addition, all standard IDL routines are available in the usual
manner. Suitable command sequences can be combined in scripts and automati­
cally performed. It is, hence, the most powerful mode of ISAP, but it needs some
expert knowledge about ISAP and IDL. A more user friendly ­ and in particular
more beginner friendly ­ mode is the GUI mode, a graphical user interface that
is built around the ISAP commands. Figure 1 shows ISAP's main GUI. The first
row provides some general information, such as object name or type of observa­
tion. The FITS header can be viewed, help pages accessed, etc. A number of
buttons in the following rows give some instrument specific informations about,
e.g., the detectors used in the observation, or the number of scans, and can be
used to extract subsets of the data.
In another column direct access is given to buttons which allow some basic
operations, like data input and output, plot control, and special functions such
as unit conversion, which operate on the AAR as a whole.
The heart of the GUI is the plot window, o#ering a completely mouse
oriented way of data visualization and selection: zooming in, getting information
about single data points and selecting parts (or all) of the data for subsequent
processing can be performed by clicking (and dragging) with one of the mouse
buttons. A large number of plotting styles can be chosen from a menu. After
selecting some data (with the right mouse button) a toolbox pops up, presenting
a variety of ISAP tools which can be applied to the selected data. The more
complex applications are simplified through separate, dedicated graphical user
interfaces, which become available on request. The ``average'' GUI, e.g., guides
the user through the necessary decisions for the type of averaging (across scans
for each detector individually, or across detectors), the bin size, or the averaging
technique (e.g., mean or median, with and without clipping., etc.). The result
can be immediately examined in two separate plot windows, which display the
data before and after application of the operation. Again, zooming in with the
mouse and individual adjustment of the plot style is possible, just like in the
main GUI.
ISAP is currently being developed by less then 10 programmers and scien­
tists (part time) at di#erent sites in Europe and the United States, on di#erent
machines under di#erent operating systems (Unix and VMS), demonstrating
the high e#ciency of programming in IDL and the high portability of IDL pro­
grammes. It also makes use of the astronomical users' library of IDL. A few
programmer's guidelines form the basis of very simple configuration control.

164 Sturm, et al.
Figure 1. The main ISAP GUI
One main advantage of this approach is, that every user can write his or her
own application. Provided the users stick to these guidelines, they can easily
add their own routines to their ISAP installation ­ or ask the ISAP team to
o#cially include them in the next release.
ISAP is publicly available via anonymous ftp and it is already in use world­
wide. Currently well over 100 astronomers have downloaded it from the o#cial
ftp sites. For many of them it has already become the main processing and
analysis tool for ISO spectra. After the proprietary period for ISO data, i.e.,
when all ISO data will be public, an even larger interest is to be expected.
ISAP has certainly some potential for future astronomical (space) missions.
Inevitably a large part of it is very instrument specific, the basic principles and
algorithms, however, as well as the whole interface, could easily be adapted for
other spectrometers.
More information about ISAP (and how to get it) can be found on the
World Wide Web: see the ISAP homepages at
http://www.ipac.caltech.edu/iso/isap/isap.html or
http://www.mpe­garching.mpg.de/iso/observer/isap/
References
Kessler, M.F. et al. 1996, A&A 315, L27
Lahuis, F., et al. 1998, this volume
Wieprecht, E., et al. 1998, this volume