ASCASIS - ASCA SIS Source Catalog
This preliminary ASCA SIS Source Catalog contains a list of point sources
detected by the Solid-state Imaging Spectrometers (SIS) on-board the ASCA
Observatory. This catalog was generated by searching for point-like sources
in all data available from the HEASARC's ASCA PUBLIC archive (ASCAPUBLIC) as
of 24 Oct 1996; and is populated by both target and serendipitous sources in
the SIS field-of-view.
For each cataloged source various information is available, which includes
the celestial coordinates of the source, the count rate, the significance of
detection, and the hardness ratio, total aperture counts, exposure time, and
start time of the observation. In addition, a set of three GIF "thumbnail"
images is available in the broad (0.5 - 12 keV), soft (2 < keV), and hard
(> 2 keV) spectral bands centered on the apparent detection. These images are
convenient for accessing the quality of the source detection.
The current catalog is preliminary, the goal of the catalog authors being to
make the SIS source list available as quickly as possible. To accomplish
this, they took an incremental approach and placed their "work in progress"
on-line, warts and all. They urge caution in using and citing these
preliminary results, as they point out that the information is not, as yet,
A full description of the ASCA archive and how to use it can be found
under the WWW at http://heasarc.gsfc.nasa.gov/docs/asca/archive.html
or in the ftp account at ftp://legacy.gsfc.nasa.gov/asca/doc/archive.txt
The current best reference for this catalog is:
Gotthelf, E.V. and White, N.E. 1997, in `X-Ray Imaging and Spectroscopy of
Cosmic Hot Plasmas', p. 31.
This catalog was generated in January 1997 by Drs. Eric Gotthelf and
Nicholas White and resulted from their search for point-like sources in all
of the then-available SIS data files in the HEASARC's Public ASCA Data Archive
as of 24 Oct 1996. The catalog is populated with both targetted and
serendipitous sources that were present in the SIS field-of-view.
Entries in the ASCASIS table have associated with them the standard ASCA
public data products for the observation in which the source was detected
(see http://heasarc.gsfc.nasa.gov/W3Browse/asca/ascamaster.html#dp_sets), as
well as three GIF files containing the soft-band, hard-band, and broad-band
images of the source that were specially constructed for this catalog.
A unique identifier for each ASCA observation set.
The source designation within this catalog. The name is derived from
the AXS prefix (for ASCA SIS X-ray source) and the apparent J2000 R.A. and
The apparent Right Ascension of the source in the selected equinox.
The apparent Declination of the source in the selected equinox.
The galactic longitude of the source.
The galactic latitude of the source.
The apparent Right Ascension of the source in the B1950 equinox
and in decimal degrees.
The apparent Declination of the source in the B1950 equinox and
in decimal degrees.
The estimated total broad-band (0.5 to 12 keV) count rate at the telescope,
The error in the estimated total broad-band (0.5 to 12 keV) count rate at the
telescope, in counts/second. (not currrently populated).
The estimated significance of this source detection. Because of the complex
ASCA mirror response function this number should be considered with caution.
The estimated hardness ratio defined as the difference over the sum of the
hard (2 - 12 keV) and soft (0.5 - 2 keV) band count rates at the source
position (= [S-H] / [S+H]).
The estimated error on the hardness ratio (not currrently populated).
The accumulated total counts within in a 6 arcmin aperture centered on the
The total "good" exposure time in seconds.
The start time of the observation.
The root filename for accessing the GIF image.
If you have questions regarding the ASCA SIS catalog, please contact Eric
Gotthelf <firstname.lastname@example.org> or Nick White
<email@example.com> for science issues. If you have questions or
problems related to the HEASARC database implementation, please contact
the HEASARC User Hotline.
If you have any problems, please consult the help
page or mail firstname.lastname@example.org