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Data analysis and Spatial Corrections

IRAF scripts have been written which utilize existing PROS tasks to make these corrections. These tasks bin a time sorted photon event list based on an assigned phase that corresponds to the 402 second period of the wobble. An image centroid is calculated for each subimage and then shifted to a common position. This procedure should be implemented for segments of an observation which have a 'stable roll angle interval' or individual obis. The fundamental limitation of this method is how many source counts you have for centroiding each binned image section. Given the normal obi length of 1000 to 2000 seconds, a count rate of 0.1 counts/sec will provide on average 10 to 20 counts if ten phase bins are selected. Once the phase binned qpoes have been shifted in x,y so as to align the source centroid, they are restacked using 'qpappend_ftsi'. This task is resident in 'xdataio' and is the same as 'qpappend' except that you can choose to keep only the temporal status intervals ('tsi') from the first file in the list to be concatenated. (Using the original 'qpappend' often resulted in an unwieldy tsi list.) An initial analysis needs to be performed to determine the stable roll angle intervals, check for a misalignment of obis and the guide star combinations.