How do I know if my observation was wobbled or not?
This one is easy: check the hardcopy output for the RA and Dec positions as a function of time. The wobble should show up as a saw-tooth wave. The full amplitude of the wobble (peak-to-peak) should be 6 arcmin, with a period of 400 seconds. (The information is stored in the .SA, .CAS (boresight corrected), and .SAS table files that are part of the ROSAT data products distribution.) Another approach is to look at the image for variations in the sharpness of the support ribs. If ALL the ribs are sharp, the observation was most likely NOT wobbled.
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