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About the HEASARC:
HEASARC Overview:
Data Formats & Software >
The Archive
Data Formats & Software
The dilemma facing the HEASARC in 1990 was that every mission up until
that point had produced data in a different format, with a different set
of analysis software, and little or no documentation. At the end of each
mission the data were in many cases scientifically useless. Combining data
from different missions was hard and there was little reuse of software
between missions. The HEASARC solution was to adopt a single,
self-describing format for all missions: the FITS standard. At the time
FITS had just been mandated as the standard for all NASA astrophysics
data. But there had been little effort made to define standard data
structures, or even decide which level of data should be formatted to this
standard. HEASARC took the lead in defining these data structures for each
level of data, a vital first step. More information on these standards can
be found on the HEASARC
FITS Working Group page.
The HEASARC worked with the next mission in line, ASCA, to create a FITS-based
multi-mission analysis system. The HEASARC first provided a portable
subroutine library to read and write FITS files. The package, known as FITSIO, was first released in
early 1992. It formed the basis for all the HEASARC software and is now
widely used throughout the world. The FTOOLS package was created to use
FITSIO and so provide an operating system-independent data analysis
package. The underlying structure utilized several ideas from IRAF and can
co-exist with IRAF packages. The FTOOLS package is now
effectively the HEASARC software archive and provides a reliable way to
maintain and distribute the relevant mission software. The XANADU package (XSPEC, XRONOS,
XIMAGE), already in wide use in the community in 1990, has been adopted
and extended by the HEASARC to provide multi-mission high-level tools for
spectral, image, and timing analysis.
At the time of the creation of the HEASARC it was controversial to propose
reformatting the original raw telemetry to FITS. But the HEASARC and ASCA
team took on this challenge and proved it was a very cost effective
approach. The advantage of reformatting the raw data was that once in
FITS, the basic data processing software could be reused for subsequent
missions. The HEASARC now recommends that all missions distribute data in
FITS format. If new standards are required then the HEASARC staff work
with the particular project to define these. It has been a notable success
for the HEASARC that smaller, less well funded missions have adopted the
HEASARC software infrastructure "as is" and used it to produce a full
analysis environment at minimal cost. The BeppoSAX mission and the USA instrument
on Argos are examples of this. The adoption of the FITS standards has made
possible a large suite of general purpose multi-mission tools, now called
HEASoft, that combines FTOOLS,
XANADU and several other useful packages.
When the Chandra, XMM-Newton and ASTRO-E missions were planning
their data systems the HEASARC organized a series of workshops to
facilitate communication between these missions. These proved to be very
helpful and, e.g., ensured that the high-level Chandra and XMM-Newton data
products could be read into the existing software packages. Both the
Chandra and XMM-Newton data systems are FITS-based and follow very closely
the "FTOOLS-approach" first developed by the HEASARC. Bringing these
software systems into the HEASARC architecture should be relatively
straightforward.
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Last modified: Monday, 19-Jun-2006 11:24:57 EDT
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