X-Ray Sources

The primary criterion for selection of X-ray sources is having identified optical counterparts, but not all do. The data in this table draw from several current source catalogs listed in the Notes and References section of The Astronomical Almanac. Prior to the 2012 edition, positions were mean places for the middle of the edition years. After consultation with members of the high-energy astronomy community, it was decided that J2000.0 coordinates were more useful. So beginning with the 2012 edition, the positions are with respect to equator and equinox J2000.0. The X-ray flux in the 2 to 10 keV range is given in mCrab or μJy in the column headed Flux. In some cases, a range of flux values is presented, representing the variability of these sources. The identified optical counterpart (or companion in the case of an X-ray binary system) is listed in the column headed ''Identified Counterpart''. The type of X-ray source is listed in the column headed ''Type'' as follows:

AGN active galactic nuclei
B burster (neutron stars in binary systems that are known to exhibit many X-ray bursts)
BHC black hole candidate (X-ray sources that are suspected of being black holes)
C cluster of galaxies
HMXB high mass X-ray binary
LMXB low mass X-ray binary
NS other neutron stars in binaries which do not burst and are not known as X-ray pulsars
P pulsar
Q quasar
SNR supernova remnants
T transient (nova-like optically)

The tabulated magnitudes are the optical magnitude of the counterpart in the V filter, unless marked by an asterisk, in which case the B magnitude is given. Variable magnitude objects are denoted by ''V''; for these objects the tabulated magnitude pertains to maximum brightness.

  • 2012 and onward X-Ray Sources in PDF and ASCII, J2000.0 coordinates
  • 2011 X-Ray Sources in PDF and ASCII
  • 2010 X-Ray Sources in PDF and ASCII
  • 2009 X-Ray Sources in PDF and ASCII
  • 2008 X-Ray Sources in PDF and ASCII
The Astronomical Almanac Online! 2020