- Copyright Notice
- Naming Convention
The author grants permission to reproduce part or all of the images maintained on this site for non-commercial educational use as long as photo credit is displayed.
|II. Naming Convention
The official "G" name for a SNR is used in this catalog when
available. For those SNRs whose "G" name is not yet defined, one is
assigned herein based on the coordinate of the center of the SNR,
as determined by visual inspection.
The Right Ascension and Declination for a SNR are resolved
through the SIMBAD database, if available. For those SNRs which are
not included in the SIMBAD database (i.e., G259+), the NED database is
Common Names were also found
through SIMBAD, though in many cases, not all of the names have been
ASCA SNR images were generated using screened data obtained from the ASCA public archive (REV2 version).
Each image is centered on the named SNR; the center of the SNR is determined by visual inspection. However, the listed Right Ascension and Declination are the coordinates resolved using either the SIMBAD or NED database.
Exposure maps were generated for each image using ascaexpo
with a maximum attitude deviation of 4 and an image rebining factor of
1 and 4, for the GIS and SIS respectively.
Matching broad- and narrow-band sky images were generated in four
energy bands using PI-channel cuts corresponding to energy ranges of
0.5-10.0 keV (broad-band), 0.5-2.5 keV (soft), 2.5-5.5 keV (med),
5.5-10.0 keV (hard), . For the SIS instrument these PI-channel cuts
are 137-1708, 137-684, 685-1264, and 1265-1708, for broad, soft, med,
hard energy-bands, respectively. The corresponding PI-channel cuts for
the GIS instrument are 42-839, 42-209, 210-460, 461-839.
The coordinates of all ASCA images on this web site have been updated
using the method described in the ASCA
coordinate correction web-page using the July 28, 2000
version of the offset coordinate table.
The ASCA sky images and exposure maps for each SNR were smoothed using
a 3 and 5 element box-car filter, for the GIS and SIS instruments
respectively. The final SNR image file is produced by dividing the
summed sky image by its respective exposure map. In the resulting image,
pixels values were set to zero if the exposure for this pixel
were less then 3 per-cent (typically) of the maximum exposure.
GIF images were produced using the pgplot plotting
subroutine package, called from a FORTRAN program. Most of the
SNRs are scaled linearly, however, on occasion, a logarithmic scaling
is used (e.g. W50).
A few GIS observation was taken in mixed image-size mode; instead
of the default 256x256 pixel image mode, data were collected using
64x64 pixels. For these cases, the 256x256 and the 64x64 pixel images
were generated separately and the image for which the exposure time is
greatest was used in the Atlas.
This site is dedicated to the exceptional creativity, talent, and
hard work of all the members of the ASCA engineering and scientific teams
that has made ASCA a remarkably successful mission.
The author is indebted to the able assistance of Vanessa Yuille in
constructing this website.
We would like to acknowledge D. A. Green's Catalogue of Galactic Supernova Remnants as a source of information and suggestions for this atlas.
This research has made use of data obtained through the High Energy Astrophysics
Science Archive Research Center Online Service, provided by the NASA/Goddard Space Flight Center.