ISOCAM Interactive Analysis User's Manual Version 5.0 - ISO - ESA

232 CHAPTER 20. ADVANCED DATA CALIBRATION
2. Divides the IMAGEs of .CUBE with .ADU SEC COEFF (so as to normalize .CUBE to
ADU/sec/gain.)
3. Subtracts the IMAGEs of .CUBE by the DARK.
4. Places the DARK in the field .DARK.
5. Finally, updates the field .CUBE UNIT to ADU/sec/gain.
The different dark correction methods are detailed below.
One important point about dark correction that the user should be aware of: corr dark
treats all the data in .CUBE as having the same integration time. However, since it is possible
to create a general PDS from data of mixed CONFIGURATIONs then the situation may arise
where the integration time is not constant throughout the .CUBE. In these cases corr dark
will fail. To avoid this problem the user should perform dark correction on the SSCD before
creating the PDS.
1. method=‘vilspa’
method: DARK model correction. Computes a dark which depends on the detector
temperature, time since activation and the integration time.
called routine: dark vilspa
PDS side effects: The field .DARK is filled with the DARK used for correction. The
IMAGEs in .CUBE are dark corrected, i.e. .CUBE is modified.
reference: Ott S. and Roman P., 2000, In preparation.
2. method=‘model’
method: DARK model correction. Compute the best dark for given revolution and timesince-activation
of ISOCAM. This is a new method and seems to yield excellent
results. It is also the default method.
called routine: darkmodel
PDS side effects: The field .DARK is filled with the DARK used for correction. The
IMAGEs in .CUBE are dark corrected, i.e. .CUBE is modified.
reference: ISOCAM dark current calibration report
3. method=‘library’ or method=‘calg’
method: CAL-G DARK correction. A DARK may be selected from the CAL-G DARK
library. As you probably know by now, the most-up-to date CAL-G files are distributed
in CDSs with the CIA system. When you create a PDS from a SSCD,
get sscdstruct automatically uses find best (see Section 20.12) to place the most
suitable DARK from the latest CIA DARK CDS into the PDS field .CALG.DARK
(see Section 15.3.2). With this method .CALG.DARK is applied to the .CUBE.
called routine: darklibrary
PDS side effects: The field .DARK is filled with the DARK used for correction. The
IMAGEs in .CUBE are dark corrected, i.e. .CUBE is modified.
reference: ISOCAM Handbook, Chapter Data processing methods, Section CALG dark.