X-RAY MONITOR ON INTEGRAL - ASTROPHYSICS IN THE 4-100 KEV BAND

The X-Ray Monitor on INTREGAL will provide images with arcminute angular resolution in the 4-100 keV band, simultaneously with the main gamma ray instruments. The limiting sensitivity for a typical 10(5) second observation will be better than one millicrab. The baseline photon detection system is a high pressure imaging proportional counter behind a coded mask (focal length 4 meters; FOV 6 degrees FWHM to match the other instruments). In addition to its support role on INTEGRAL (providing fine imaging and simultaneous X-Ray flux measurements) the spectral resolution and sensitivity are sufficient to make it a useful stand-alone instrument. In particular it will be able to monitor the iron lines seen in both Galactic and extra-Galactic sources, and relate these to the behavior of the hard continuum, seen in the other instruments. It will also enable the study of hard X-Ray continua of many Galactic and extra-Galactic sources: specifically the search for cyclotron lines in Galactic binaries, Compton 'humps', and other features in AGN spectra, perhaps evidence for pair processes. Because of its high sensitivity it will be used to scan the Galactic plane once every few days to detect the onset of transients (potential 'hard tail' objects), which can then be observed in detail by the Gamma ray instruments.