indicates which apertures place the target at the geometric center of the subarray, and which apertures place it at a substantial offset from the center. Table 6.1: Predefined apertures for WFC3/UVIS (details can be found in the Phase II Proposal Instructions). If “-SUB” is omitted from the quad aperture name (i.e., UVIS-QUAD, UVIS-QUAD-FIX), the target is positioned in the proper quadrant for the bandpass requested in the filter parameter, but the entire frame, both CCDs, is still read out. Furthermore, specification of the subarray quad aperture (UVIS-QUAD-SUB) instructs the ground system to read out only the 2k ×2k quadrant of interest. This combination of quad aperture and quad filter ensures that the target is automatically placed in the correct quadrant for imaging with the requested quad bandpass. For the special case of quad filters (which are optical elements that include four different bandpasses simultaneously, one bandpass per WFC3 UVIS quadrant), the observer must select one of the “QUAD” Aperture values in the Phase II proposal, in conjunction with the desired quad filter via the filter parameter.
0 kommentar(er)
