Use two XYmean.table,parlab files (such as compiled in runs of the bash script "ds9_imstats_fitslist") to compute mean X,Y offsets. Recall that the role of ds9_imstats_fitslist is to compute image centroids for multiple sources on multiple images. The reult of such a run is the XYmean.table file. The purpose of this code is to take two such table files and compute the image offsets using all of the avilable objects measured in the two image sets.
% table_XY_offsets.sh --help Usage: table_XY_offsets.sh tabA tabB XYmean xmean ymean xme yme N arg1 - basename of table 1 (A for A.table) arg2 - basename of table 2 (A for A.table) arg3 - param name for X position arg4 - param name for Y position arg5 - param name for error in X position arg6 - param name for error in Y position arg7 - run in verbose/debug mode (Y/N)The resultant output is a list of statistics for the mean linear offset (i.e. the value of R = sqrt{dX^2 + dY^2}).
Note that PAS images have information on X,Y centroids of at least one star in the image headers. You can do the same sort of calculation shown here using PAS images directly with pas_XY_offsets.sh.