Analysis of the in-flight calibration data collected during ISO's performance verification phase and during the subsequent routine operations have shown that a number of pre-flight assumptions concerning the performance and operation of the ISOPHOT instrument must be revised in order to improve the quality of the observations. In particular, the effects of ionizing radiation and detector responsivity drifts should be considered when preparing ISOPHOT observations.
This Addendum to the ISOPHOT Observer's Manual has been written in order to give the observer new information on the actual performance of the instrument as well as new recommendations how to make best use of the existing or revised observing modes.
This has led to the following changes with respect to the information presented in the ISOPHOT Observer's Manual Version 3.1 (hereafter referred to as IOM3.1):
In the next Section we list which sections in the IOM3.1 have been affected by the new ISOPHOT performance description.