Whenever possible, uncertainties are included in the OLP products. However, the formal propagation of these uncertainties does not yield a reasonable error estimate in the photometry. This is due to the presence of different types of errors: statistical uncertainties, systematic uncertainties, and photometric bias. The relative contribution of these components in the processing chain depends on the details of the measurement mode.
For an estimate of the total uncertainty associated with a specific measurement the observer is referred to the previous Chapter9 and the documents `ISOPHOT Error Budgets' by Laureijs & Klaas 1999, [31] and `ISOPHOT Calibration Accuracies' by Klaas et al. 2002, [26].
Caveat: The PHT OLP software does only provide an uncertainty based on the statistical evaluation of the signals. No estimates are given of the systematic uncertainties introduced by calibration steps. Therefore, OLP 10 uncertainties are `minimal' errors. It is essential to refer to special documentation which provides an overview of the uncertainties introduced step by step. These depend on the exact observing conditions and evaluation steps which may even not be completed inside OLP, e.g. background subtraction in maps or from independent staring measurements.