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polnorm stsdas.hst_calib.fos.spec_polar



polnorm -- Normalize Stokes Q, U, and V by Stokes I.


polnorm input output


The polnorm task takes an FOS polarimetry (c3h) file and normalizes the Stokes Q, U, and V parameter spectra by the Stokes I (flux) spectrum. The errors in the normalized spectra are also calculated. The ouput image is a copy of the input image with the Stokes Q, U, and V and their error spectra replaced by the normalized values. All four sets of Stokes parameter spectra are operated on, i.e. those for pass direction 1, pass direction 2, the merged, and the merged and corrected data sets.

Note that the algorithms used in the tasks polave, polcalc, and polbin to compute polarization quantities from Stokes parameters all assume that the input Stokes QUV parameters have NOT yet been normalized by Stokes I. Therefore the polnorm task can only be used on polarimetry files AFTER all desired processing by polave, polcalc, or polbin has been completed.

Because the errors in the Stokes parameters Q, U, and V are independent from those in I, the errors in the normalized spectra are calculated as follows (for Stokes Q, for example):

                             { Qerr**2   Ierr**2 Q**2 }
      normalized Qerr = sqrt { ------- + -------*---- }
                             {  I**2      I**2   I**2 }

If the values of Stokes I and Ierr for a given pixel are zero, the normalized Stokes QUV and their error values are set to zero.


input [file name]
Input image(s). May be a list or a file name template. If the input image name extension is not given, an extension of c3h is assumed.
output [file name]
Output image(s). May be a list, but must contain the same number of elements as the input image list. If the output image name extension is not given, an extension of c3h is assumed.
(verbose = yes) [boolean]
Print operations as they are performed?


1. Calculate normalized Q, U, and V for the FOS polarization image y15v0403t.c3h and store the results in y15v0403t_norm.c3h.

     sp> polnorm y15v0403t y15v0403t_norm 



Author: Howard Bushouse, STSDAS


For assistance using this or any other tasks, please contact or call the help desk at 410-338-1082.


polave, polbin, polcalc

Type "help spec_polar opt=sys" for a tutorial on FOS polarimetry datasets and the use of the spec_polar tasks in a coordinated fashion.

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