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10.13 Residual Flat-Field Structures in PHT22 Raster Maps

A statistical flat-field method is applied to remove flat-field residuals in PHT22 maps with more than 20 raster points, see Section 8.5.1. Smaller raster maps are usually obtained for photometry of individual sources centred in the map, the so-called mini-map photometry. Dedicated analysis methods have been developed for mini-maps. The following caveat applies to mapping measurements executed with AOT P22 in raster mode:

Caveat:  Temporal variations of the flat-field in case of C100 maps limit the ability of faint source detections and photometry on low sky background levels.

ISO Handbook Volume IV (PHT), Version 2.0.1, SAI/1999-069/Dc