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Next: 13.10 FCS power calibration
Up: 13 Calibration G Products
Previous: 13.8 Vignetting Corrections
Description Parameter: none
Processing Level: SPD, AAR
Usage in processing: Section 7.3.9, 8.4.6
File Type: FITS Image
Units: Dimensionless
File Names: PPCHOPCOR, PC1CHOPCOR, PC2CHOPCOR
The signal difference between the on- and off-chopper plateaux is
observed to be lower than the signal difference obtained from the same
source-background position combination in staring or nodding mode.
The effect is attributed to the detector transient responsivity
behaviour of the detectors which underestimates the on-signal and
overestimates the background signal. The calibration files contain
for each detector the parameters necessary to correct the difference signal
for the signal loss. The parameters are a function of the chopper plateau
time. The correction is applied by dividing by a given parameter.
For all chopped signal corrections, the following FITS keywords are common:
NAXIS = 3
TYPE = REAL*4
AXIS Length Description 1 3 PHT-P1,P2,P3 2 8 Chopper plateau time given by n, t=2n-1 s, n=1,8 3 2 Correction and uncertainty
AXIS Length Description 1 9 C100 pixels in the same order as in SPD 2 8 Chopper plateau time given by n, t=2n-1 s, n=1,8 3 2 Correction and uncertainty
AXIS Length Description 1 4 C200 pixels in the same order as in SPD 2 8 Chopper plateau time given by n, t=2n-1 s, n=1,8 3 2 Correction and uncertainty
ISOPHOT Data Users Manual, Version 4.1, SAI/95-220/Dc