... Figure 1.1 also illustrates the projected orientation of the WFPC2 CCDs onto the sky. ... The WFPC2 has two readout formats: full single pixel resolution (FULL Mode), and 2x2 pixel summation (AREA Mode which is obtained by specifying the optional parameter SUM=2x2 as described in the Proposal Instructions). Each line of science data is started with two words of engineering data, followed by 800 (FULL) or 400 (AREA) 16-bit positive numbers as read from the CCDs (with 12 significant bits). ...