The relation between the rows and columns for the four CCDs is shown in Figure 1.1 , where the short arrows on each CCD are placed near pixel (1,1) and point in the -Y (readout) direction. ... 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). ...