Improved positions for unidentified INTEGRAL sources in the 4th INTEGRAL/IBIS sky survey catalogue.
The 4th INTEGRAL/IBIS sky survey catalogue (Bird et al. ApJS 186, 1, 2010, see
also INTEGRAL Picture of the Month October 2009) contains more than 700 sources
in the 17-100 keV energy range. About 29% of the catalogued sources are unidentified
and/or unclassified.
As part of the ongoing campaign to identify the remaining unknown sources,
the use of X-ray catalogues is extremely important. By performing a statistical
correlation analysis between the gamma-ray source positions and the X-ray lists, it
is possible to find some objects which have X-ray counterparts at high statistical
probabilities.
The X-ray sources have in general a much more precise position and this can then
be used for follow-up observations at other wavelengths which may then lead to the
source classification.
The picture shows one example: the unidentified 4th catalogue object IGR J17488-2338
(green IBIS location error circle) can be associated with the XMM Slew Survey source
XMMSL1 J174838.8 -233537 (white XMM location error circle) which is centred on the
nucleus of a bright radio source (NVSS, 1.4 GHz) with a double lobe morphology as
shown.
Thus the counterpart of this INTEGRAL source can be identified as a new active galaxy
detected behind the Galactic plane.
Further information can be found in: J.B. Stephen et al., Astronomical Telegram
(ATEL) #2441, 16 Feb 2010
