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GALCENPSPC - ROSAT PSPC Galactic Center Soft X-Ray Source Catalog

HEASARC
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Overview

This table contains a catalog of 107 point-like X-ray sources derived from a systematic analysis of all the ROSAT PSPC observations of the Galactic Center region performed in 1992-1993. Besides Sgr A*, the massive black hole at the galactic center, 41 X-ray sources have been positionally associated with already classified objects. Twenty are identified with foreground stars and five with known Low Mass X-ray Binaries (LMXBs). The majority of the sources in this catalog still remains unidentified. They are hard and/or severely absorbed and probably represent a large population of X-ray binaries located in the galactic center region, accreting at low accretion rates, and still largely unknown.

Analyses were performed in 4 different energy ranges: 0.1 - 2.4 keV (PSPC channels 8 - 240, the total energy band T), 0.1 - 0.4 keV (PSPC channels 8 - 40, the soft energy band S), 0.5 - 0.9 keV (PSPC channels 52 - 90, the medium energy band), and 0.9 - 2.4 keV (PSPC channels 91 - 240, the hard energy band H). A maximum likelihood method was applied to the merged photon lists in each band. Only a detection liklihood larger than 10 (corresponding to a probability of a chance detection smaller than e-10) was considered to be a true source.


Catalog Bibcode

2001A&A...368..835S

References

A catalogue of soft X-ray sources in the Galactic Center region.
    Sidoli L., Belloni T., Mereghetti S.
   <Astron. Astrophys. 368, 835 (2001)>
   =2001A&A...368..835S

Provenance

This table was created by the HEASARC in March 2012 based on CDS Catalog J/A+A/368/835 file table3.dat.

Parameters

Source_Number
A unique identification number for each source in the catalog in order of increasing J2000.0 Right Ascension.

Name
The designation for sources in this catalog as recommended by the Dictionary of Nomenclature of Celestial Objects, namely '[SBM2001] nnn' where the prefix stands for Sidoli, Belloni, Mereghetti 2001 and 'nnn' is the source number.

Pt94_Source_Number
The corresponding source number in Predehl & Truemper (1994, A&A, 290, L29).

RA
The Right Ascension of the X-ray source in the selected equinox. This was given in J2000.0 equatorial coordinates to a precision of 0.1 seconds of time in the original table.

Dec
The Declination of the X-ray source in the selected equinox. This was given in J2000.0 equatorial coordinates to a precision of 0.1 arcseconds in the original table.

LII
The Galactic Longitude of the X-ray source.

BII
The Galactic Latitude of the X-ray source.

Error_Radius
The rms uncertainty in the position of the X-ray source, in arcseconds.

Count_Rate_Limit
This parameter is set to '<' if the corresponding parameter value is a 2-sigma upper limit rather than an actual detection.

Count_Rate
The count rate of the X-ray source in the total energy band (0.1 - 2.4 keV), in ct s-1 (converted from the ct ks-1 given in the original table), except if the count_rate_flag parameter value is 'H', in which case it is the hard-band (0.9 - 2.4 keV) count rate, 'M', in which case it is the medium-band (0.5 - 0.9 keV) count rate, or 'S', in which case it is the soft-band (0.1 - 0.4 keV) count rate,

Count_Rate_Error
The rms uncertainty in the count rate of the X-ray source, in ct s-1 (converted from the ct ks-1 given in the original table).

Count_Rate_Flag
This parameter is set to 'H', 'M' or 'S' to indicate the band (see Overview above) in which the source was detected. It is possible that a source had an upper limit in the total energy band, but was detected in one of the single energy bands. This is due to the energy-dependent background: faint sources detected, for example in the hard energy range, could have been missed in the total energy band due to a higher background level. For such sources, the count rate in the energy band where the detection was made is reported in the count rate parameter.

Log_SB_Over_HB_Limit
This parameter is set to '<' if the corresponding parameter value is an upper limit or to '>' if the corresponding parameter value is an lower limit, else it is an actual value.

Log_SB_Over_HB
The logarithm of the softness ratio S/H, i.e., the log of the ratio of (0.1 - 0.4 keV) count rate to the (0.9 - 2.4 keV) count rate. A few source were detected in the total energy band but had only upper limits in all the single energy ranges, in which case this parameter is left blank.

Log_SB_Over_HB_Error
The rms uncertainty in the logarithm of the softness ratio S/H.

Log_MB_Over_HB_Limit
This parameter is set to '<' if the corresponding parameter value is an upper limit or to '>' if the corresponding parameter value is an lower limit, else it is an actual value.

Log_MB_Over_HB
The logarithm of the softness ratio M/H, i.e., the log of the ratio of (0.5 - 0.9 keV) count rate to the (0.9 - 2.4 keV) count rate. A few source were detected in the total energy band but had only upper limits in all the single energy ranges, in which case this parameter is left blank.

Log_MB_Over_HB_Error
The rms uncertainty in the logarithm of the softness ratio M/H.

Source_Notes
Notes on other source identifications, counterparts at other wavelengths, etc. In the notes, the probable identifications based on the cross-correlation with the SIMBAD database is reported; in parentheses, the authors indicate the offset, spectral type, B and V magnitude for stars. The meaning of the other symbols is:

       Al* = Eclipsing Binary of Algol type
       V*  = variable star
       bL* = Eclipsing Binary of beta Lyr type
       *i* = star in double system
       Em* = emission line star
  

Contact Person

Questions regarding the GALCENPSPC database table can be addressed to the HEASARC User Hotline.

Page Author: Browse Software Development Team
Last Modified: 20-Mar-2012