... Data . ... WFPC2 Home . ... A common analysis problem for WFPC2 observations is the subtraction of the PSF from a much fainter background object. ... Make PSF observations at the same location. ... Make PSF observations using the same filter, and using a star with a similar spectrum. ... Observers with M(target) -- M(bright star) larger than the limiting values in the center column should be prepared to use PSF subtraction (i.e., using PSF from Tiny Tim, the archives, or their own observations). ...