XMM-Newton Science Analysis System


eposcorr (eposcorr-3.13) [xmmsas_20230412_1735-21.0.0]

Description

The eposcorr task reads the X-ray source positions from an input fits-file and correlates those with the positions from an optical source catalogue. The correlation algorithm checks whether there are offsets in RA and DEC which optimize the correlation. To do this a particular statistic is used and its value calculated for a grid of 30x30 offset values with a resolution, which can be controlled by input parameters. If demanded a similar grid search is done for roll angle errors. In that case, first a 3dimensional grid search will be done and then several iterations with alternating RA/DEC offsets and rotational offsets are made. The optimum offsets are then used to correct the input source positions which will be added as separate columns to input X-ray source catalogue.