I used AP script to measure the flux of an image and saved the results in a Image table. The documentation shows the CATRA and IMGRA columns are the catalog RA position and the measured RA position on the image respectively. I used Exctract stars from catalog, and used the Gaia DR2 catalog. I then loaded the table into a spreadsheet and had excel calculate the difference between CATRA and IMGRA which should give the drift of the star from J2000 to JNow, but the results show 0 difference for all stars. Shouldn't I see some sort of proper motion drift or difference between catalog and actual position on the plate?
Craig
Craig