In the data products derived for the FPs, some data can be marked as bad, although there is in principle nothing wrong with this data in the SPD file. The reason for the discrepancy lies in the way the responsivity correction is performed for FP data. The processing software determines for each line where the FP is expected to be for the position of the grating that was used. This expected FP position depends on the order that the FP is working in. The software then checks that the FP was indeed scanned around this expected position. If this is the case, the responsivity correction is done for this grating and FP position. If the FP however was not scanned around the expected value, the software flags the data as invalid, since no valid responsivity can be found for this FP position.
With the current calibration files for some wavelength regions (especially at points where the order of the FP that is used changes) the FP position can not be found in the calibration files, although the FP was scanned over the correct range. This is due to a difference in the FP order between the processing software and the AOT planning software. Although the new calibration files, that are used for Version 6 of the Off-line processing, have been derived from the uplink files, there still are some problems with the order selection remaining. To solve these remaining cases will probably require significant changes to the processing software.
The observer can check if there were problems with the responsivity correction for his data by checking the status words in the Auto Analysis product file (see section 8.2.8).