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Polarimetry

The presence of polarimetric measurements in the IMB-FITS file is described in the POLAR column of the BACKEND table. For a non-polarimetric scan, all the chunks in the POLAR column have the NONE value. For a polarimetric scan, values can be NONE, AXIS, REAL or IMAG (note that non-polarimetric chunks -NONE- can be mixed with polarimetric ones).

When processing a polarimetric scan, MRTCAL will offer 2 modes:

  1. full polarimetry support, with calibration of both self-products (AXIS i.e. HH and VV) and cross-products (REAL and IMAG i.e. HV and VH), plus non-polarimetric data (NONE),
  2. minimal support, i.e. calibration of self-products and non-polarimetric data (AXIS and NONE).
In order to achieve the second point, MRTCAL skips the REAL and IMAG chunks at read time of the BACKEND table.

Finally, the polarimetric status (does this scan contains polarimetric data?) is saved in the index file. The command MFIND /POLARIMETRY YES|NO|* allows to make the desired selections in this context.



Gildas manager 2015-03-19