| Description: This attribute indicates how pixels have been combined on the detector during readout. A value of 2 indicates that pixels have been combined in 2x2 squares; A value of 1 indicates that the detector was read out at full resolution. For many HST products this is the value of BINAXIS1 or BINAXIS2, whichever is larger. (HST binning modes need not be square, so this attribute cannot fully capture all the possibilities. Nevertheless, in practice, BINAXIS1 and BINAXIS2 are almost always equal.) Note that, for some HST products, the values of BINAXIS1 and BINAXIS2 can be found in the global FITS header; for others, it is found in the second header, which is the first data header. For WFPC and WFPC2, this attribute is derived from the value of MODE: - MODE = FULL -> binning_mode = 1 - MODE = AREA -> binning_mode = 2 For instruments that do not support binning options, the value of this attribute is always 1. |