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2.4 Calibration Accuracies Achievable by Interactive Data Processing

As the OLP processing is automatic using default parameters for all processed measurements, it allows a homogeneous comparison of data sets of the same type of observing mode and hence to derive a set of commonly applicable uncertainties. Those are not subject to individual preferences of parameter settings during interactive processing and do not require the knowledge of special data reduction tricks. In general, standard OLP-type batch processing in ISOPHOT Interactive Analysis (PIA) provides identical accuracies.

The provision of a percentage number characterizing which improvements in calibration accuracy can be obtained by careful interactive processing is impossible, since so far no comprehensive systematic investigation was performed. Interactive Analysis uses the same set of general calibration files (cal-G) as OLP. The limitations due to photometric bias, e.g. the accuracy of the standard source fluxes, fully apply to interactive calibration, too. One can expect,however, to achieve a higher accuracy with IA for the following cases:

1)

measurements with signal transients which do not stabilise during the measurement time, but which are long enough to perform a reasonable transient fit.

2)

flat-fielding of maps, depending on the sampling mode and the dynamic range.

3)

correction of non-linear signal drifts in maps.

4)

detection of faint sources by refined deglitching and filtering.

The gain in final calibration accuracy with interactive analysis has, however, to be determined on a case by case basis.