NAME instrument data file (IDF), default name suffix .ins. DESCRIPTION The instrument data file (IDF) is the resultfile of instrument. It stores a description of some Wide Field Camera properties and contains references to other calibration datafiles. Amongst these is the name of the mask file and the appropriate detector file. IDF FITS structure ext.name type dim description PRIMARY --- 0 keyword data only. mask pattern, binned to match detector pixelsize, WFCbinmask-32 nx ny first plane computed with open maskelement set to 1, 2 closed element to 0, second plane vice versa. WFCdftmask-32 nx ny discrete Fourier transform of the original mask 2 pattern, planes differing as above. first plane : for each pixel in the sky, the reciprocal of the total detector area (cm2) seen WFCcf -32 nx ny through open maskelements. 2 second plane: for each pixel in the sky, the reciprocal of the area (not) seen through closed maskelements.