This chapter summarizes the changes from the nominal, pre-launch performance of the satellite and the instruments as determined from PV and AO data.
More detailed information is given in the relevant instrument chapters.
The PSF and effective area, on and off axis, are essentially as described in the first Technical Description . 3.2 GIS Performance As far as we can tell, the GIS has been performing as expected, in general. The energy resolution, position determination, background and useable field of view are all very close to the values predicted from ground calibrations. Inflight observations have, however, emphasized the need to avoid placing point-source targets beneath the wires of the grid which supports the window. This is analogous to the gaps between the SIS CCDs, and both effects are taken care of in the same way, i.e., by offsetting the pointing position.