Improved mosaicking capabilities with JEM-X
  Observations performed by INTEGRAL are typically subdivided in kilo-seconds individual pointings. A mosaic software has been developed at the Danish Space Research Institute to combine sky images from different pointings with significantly improved capabilities compared to the available software. This software takes account of the specifics of the JEM-X instrument, such as the vignetting effects due to its collimator and its mask structure. It calculates the weighted contribution of each pixel from each input sky images to be added in order to maximise the signal/noise ratio of each pixel in the combined sky image. The software produces mosaic'ed maps with the source signal and of the noise in each pixel, and is used as a tool to find new X-rays sources that are too weak to be seen in individual pointings. 
J. Chenevez, N. Lund, N. J. Westergaard, C. Budtz-Joergensen, P.   Kretschmar, R. Walter