ASCAGPS: Help
ASCAGPS - ASCA Galactic Plane Survey X-Ray Source Catalog |
Sugizaki et al. (2001) have published a study of faint X-ray
sources that were resolved in the ASCA Galactic Plane Survey and
their contribution to the galactic ridge X-ray emission, and the present
database contains their list of discrete sources. The X-ray emission from the
central region of the Galactic plane, |l|<~45 degrees and |b|<~0.4 degrees, was
studied in the 0.7 to 10 keV energy band with a spatial resolution of ~3' with
the Advanced Satellite for Cosmology and Astrophysics (ASCA) observatory.
The authors developed a new analysis method for the ASCA data to resolve
discrete sources from the extended Galactic ridge X-ray emission (GRXE).
Using the ASCA Gas Imaging Spectrometers (GISs), they successfully resolved
163 discrete sources with X-ray fluxes down to 10^-12.5^ergs/cm^2/s and
determined the intensity variations of the GRXE as a function of the Galactic
longitude with a spatial resolution of about 1 degree.
2001ApJS..134...77S
Sugizaki M., Mitsuda K., Kaneda H., Matsuzaki K., Yamauchi S., Koyama K.
<Astrophys. J. Suppl. Ser. 134, 77 (2001)>
=2001ApJS..134...77S
This database was created by the HEASARC in December 2001 based
on the ADC/CDS Catalog J/ApJS/134/77/table2.dat.
Position_Flag
This is a flag that is set to 'Y' to denote reduced accuracy
because the source location is near the edge of the field of view.
Name
The name of the X-ray source using the prefix AX (for ASCA X-ray)
and the J2000 equatorial coordinates.
RA
The Right Ascension of the X-ray source in the requested equinox. The RA
was given in J2000 coordinates in decimal degrees and with a precision of
0.001 degrees (0.06 arcminutes) in the originating table.
Dec
The Declination of the X-ray source in the requested equinox. The Dec.
was given in J2000 coordinates in decimal degrees and with a precision of
0.001 degrees (0.06 arcminutes) in the originating table.
LII
The Galactic Longitude of the X-ray source.
BII
The Galactic Latitude of the X-ray source.
Count_Rate_1
The count rate observed at the GIS nominal position in the 0.7
- 2 keV energy band as obtained from image fitting analysis, in units of counts
per second per GIS (notice that in the published paper the units used were
counts per kilosecond per GIS). A null value for this parameter means that
no source candidate was detected in this energy band.
SNR_1
The significance of the source detection in the 0.7 - 2 keV energy
band, defined as the ratio of the best-fit flux over the 1-sigma error in
the flux.
Count_Rate_3
The count rate observed at the GIS nominal position in the 0.7
- 7 keV energy band as obtained from image fitting analysis, in units of counts
per second per GIS (notice that in the published paper the units used were
counts per kilosecond per GIS). A null value for this parameter means that
no source candidate was detected in this energy band.
SNR_3
The significance of the source detection in the 0.7 - 7 keV energy
band, defined as the ratio of the best-fit flux over the 1-sigma error in
the flux.
Count_Rate_2
The count rate observed at the GIS nominal position in the 2 -
10 keV energy band as obtained from image fitting analysis, in units of counts
per second per GIS (notice that in the published paper the units used were
counts per kilosecond per GIS). A null value for this parameter means that
no source candidate was detected in this energy band.
SNR_2
The significance of the source detection in the 2 - 10 keV energy
band, defined as the ratio of the best-fit flux over the 1-sigma error in
the flux.
Model_Flux
The best-fit value of the flux in the 0.7 - 10 keV energy band
obtained by fitting the source spectrum with a simple absorbed power law model,
in units of erg/cm^2/s, for those sources having a significance above 5 sigma.
Spectral_Index
The best-fit value of the photon index obtained by fitting
the source spectrum with a simple absorbed power law model, for those sources
having a significance above 5 sigma.
Spectral_Index_Poserr
The upper 90% confidence limit or positive error
of the best-fit value of the photon index obtained by fitting the source
spectrum with an absorbed power law model. Null values for the errors are used
to indicate that the best-fit power-law model is unacceptable within 97%
confidence limits (reduced chi_nu value of less than 2).
Spectral_Index_Negerr
The lower 90% confidence limit or negative error of
the best-fit value of the photon index obtained by fitting the source
spectrum with an absorbed power law model. Null values for the errors are used
to indicate that the best-fit power-law model is unacceptable within 97%
confidence limits (reduced chi_nu value of less than 2).
NH
The best-fit value of the absorption column density, in units of
hydrogen atoms cm^-2, obtained by fitting the source spectrum with a
simple absorbed power law model.
NH_Poserr
The upper 90% confidence limit or positive error of the best-fit
value of the absorption column density, in units of hydrogen atoms cm^-2,
obtained by fitting the source spectrum with an absorbed power law model. Null
values for the errors are used to indicate that the best-fit power-law model
is unacceptable within 97% confidence limits (reduced chi_nu value of less
than 2).
NH_Negerr
The lower 90% confidence limit or negative error of the best-fit
value of the absorption column density, in units of hydrogen atoms cm^-2,
obtained by fitting the source spectrum with an absorbed power law model. Null
values for the errors are used to indicate that the best-fit power-law model
is unacceptable within 97% confidence limits (reduced chi_nu value of less
than 2).
Reduced_Chi_Nu
The reduced chi-squared value, (Chi^2)_nu, for 10 degrees
of freedom, of the best-fit absorbed power-law model.
Cross_ID
This field contains identified catalog sources within the 1'
positional determination accuracy of the ASCA X-ray source from the Einstein
IPC X-Ray Source (2E) Catalog, the ROSAT All-Sky Survey Bright Source (1RXS)
Catalog, the Green Galactic SNR (G) Catalog, and/or catalogs of optical stars
from the SIMBAD database (SIM).
Questions regarding the ASCAGPS database table can be addressed to the
HEASARC User Hotline.
If you have any problems, please consult the help
page or mail ledas-help@star.le.ac.uk
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