Photometric Mapping with ISOPHOT using the “P32” Astronomical Observation Template

The “P32” Astronomical Observation Template (AOT) provided a means to map large areas of sky (up to 45×45 arcmin) in the far-infrared (FIR) at high redundancy and with sampling close to the Nyquist limit using the ISOPHOT C100 (3×3) and C200 (2×2) detector arrays on board the Infrared Space Observatory (ISO). However, the transient response behaviour of the Ga:Ge detectors, if uncorrected, can lead to severe systematic photometric errors and distortions of source morphology on maps. We describe the basic concepts of an algorithm which can successfully correct for transient response artifacts in P32 observations. Examples are given to demonstrate the photometric and imaging performance of ISOPHOT P32 observations of point and extended sources corrected using the algorithm. For extended sources we give the integrated flux densities of the nearby galaxies NGC 6946, M 51 and M 101. and an image of M 101 at 100 μm.