The circular structures (middle panel) in the enhanced background image are
artifacts related to the absorption of hard X-ray photons by the glue used to
mount the instrument coded mask on its supporting structure. The intensity of
these artifacts is of the order of 0.2% of that of the brightest source in the
field of view. Thanks to an extensive in-flight calibration effort this glue
could be modeled much better, reducing the artifacts by a factor of 10 (right
panel).
In this image (right panel), new faint hard X-ray sources could be detected for
the first time. The source in the green circle is two thousand times fainter than
Cygnus X-1.
The OSA 9 software package is available at the INTEGRAL Science Data Centre
( http://www.isdc.unige.ch/integral/ ).
Pictures © Roland Walter/ISDC