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

20.3. CALIBRATING AN SSCD 241
Figure 20.1: Comparison of standard vs. improved processing of observations using
the small Fabry mirror
Left: .MOSAIC of standard processing.
Right: .MOSAIC of improved processing. The uneven appearance of the .MOSAIC is gone.
20.3 Calibrating an SSCD
In most cases users are only interested in calibrating a PDS and the SSCD is quickly discarded.
However, there are certain situations where the calibration of an SSCD is very more useful.
Mostly these cases require that contiguous data over as a long a time-scale as possible is available
for input to the calibration routines. Remember that a PDS does not necessarily hold
contiguous data – see Section 13.1.1 for details of the limitations of a PDS. In particular, data
from polarization observations are best calibrated using an SSCD – see Chapter 8 for an example
of this.
Here we have an example of how and why you would calibrate an SSCD. This example
illustrates the usage of the VilSpa dark correction and the Fouks-Schubert transient correction
method (see Section 20.2.3). This transient correction method works best with the contiguous
data that is provided in an SSCD. We use the same dataset as in Chapter 3.
1. Create the SSCD and SCDs:
CIA> spdtoscd, ’cisp02600506.fits’, sscd, dir=’$cia_vers/test’, /nowrite
CIA> sscd_info, sscd, /deg
43 SCDs in the SSCD: CSSC026005060101_98052614571745
seq channel mode fltrwhl pfov tint gain offset size ra dec
0 LW IDLE LW2 6.0 25.20 1 512 1 ******* *******
1 LW IDLE LW2 6.0 2.10 2 512 1 ******* *******
2 LW OBS LW2 3.0 5.04 1 512 46 180.498 -18.849
3 LW OBS LW2 3.0 5.04 1 512 24 180.490 -18.871
4 LW OBS LW2 3.0 5.04 1 512 24 180.482 -18.893
5 LW OBS LW2 3.0 5.04 1 512 24 180.473 -18.915