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

52 CHAPTER 8. POLARIZATION OBSERVATION (CAM05/DEDICATED CAM99)
4. Flat-field the EXPOSUREs. Firstly, identify the entrance wheel associated with each
EXPOSURE. Restore the appropriate flat-field image from the set of polarization flatfields
distributed with CIA and supply as input to corr flat.
5. Convert the pixel values to milli-janskys (mJy) with conv flux and perform photometry
on the EXPOSUREs and/or MOSAIC images. One may use xphot for this purpose.
6. Use get polar weight to determine the polar weight factors and comp stokes to calculate
the Stokes parameters.
8.2.2 Slice and perform core calibration
Slicing is straightforward:
CIA> spdtoscd, ’cisp35600501.fits’, sscd, dir=’$cia_vers/test’, /nowrite
Core calibration may be done with the usual routines except we work directly on the SSCD
rather than on a PDS. Later you will see that the PDS will contain SCDs extracted from different
points within the SSCD or observation, i.e. the PDS will not contain contiguously acquired data.
Because core calibration works best on contiguous data we must postpone the freezing of the
data in a PDS until after the core calibration.
CIA> corr_dark, sscd
CIA> deglitch, sscd
CIA> stabilize, sscd
8.2.3 Clean the SSCD
Cleaning the SSCD is a difficult task that must be done manually. A single polarization observation
may be a combination of multiple rasters with changing entrance wheel at each raster
point id or each raster position. The steps for this observation are as follows.
1. First list all the SCDs in the observation:
CIA> sscd_info, sscd, /pol
50 SCDs in the SSCD: CSSC356005010001_00020117264901
seq entwhl mode fltrwhl pfov tint gain size m_raster n_raster
0 HOLE OBS LW2 6.0 25.20 1 1 1 1
1 HOLE IDLE LW2 6.0 2.10 1 11 1 1
2 HOLE OBS LW2 3.0 2.10 1 102 1 1
3 HOLE OBS LW2 3.0 2.10 1 92 2 1
4 HOLE OBS LW2 3.0 2.10 1 92 2 2
5 HOLE OBS LW2 3.0 2.10 1 97 1 2
6 HOLE OBS LW2 3.0 2.10 1 13 1 1
7 POLARIZOR 1 OBS LW2 3.0 2.10 1 78 1 1
8 POLARIZOR 2 OBS LW2 3.0 2.10 1 77 1 1
9 POLARIZOR 3 OBS LW2 3.0 2.10 1 1 1 1
10 POLARIZOR 3 OBS LW2 3.0 2.10 1 78 1 1
11 POLARIZOR 1 OBS LW2 3.0 2.10 1 78 1 1
12 POLARIZOR 2 OBS LW2 3.0 2.10 1 77 1 1