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

Chapter 8
Polarization observation
(CAM05/dedicated CAM99)
8.1 Description of the observation
The data used here is from a CAM polarization observation of the object HIC085371. This
observation is basically a 2 × 2 raster observation, though at each raster pointing the entrance
wheel cycles through the 3 polarizors 3 times. Hence there are many SCDs for this observations:
2 × 2 × 3 × 3 in addition to several IDLE and other uninteresting SCDs. This chapter provides
a good example of the technique of calibrating an SSCD.
8.2 Data analysis
It is assumed in this section that you have read Chapter 3. Generally concepts described in that
section will not be re-described here. In this example, it is necessary to calibrate the SSCD, and
not the PDS. This is because the polarization data will no longer be contiguous when it is frozen
in a PDS – see Section 13.1.1 for details of the limitations of a PDS. This will become more
obvious later in the chapter when we get to the SSCD cleaning stage. For more on calibration
of SSCDs see Section 20.3.
8.2.1 Overview of calibration steps
The steps involved in the calibration of data from this polarization observation may be summarized
as:
1. Slice in the usual way using one of the slicing routines, e.g. spdtoscd or x slicer. Perform
dark, deglitching and transient correction on the SSCD using the routines corr dark,
deglitch and stabilize.
2. After the core calibration steps are complete we manually clean and combine SSCDs and
SCDs before attempting to create a PDS. This step is very much dependent on how the
observation was programmed.
3. Now freeze the SSCD into a raster PDS with get sscdraster and reduce the IMAGEs to
EXPOSUREs with reduce.
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