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polnorm stsdas.hst_calib.fos.spec_polar


NAME · USAGE · DESCRIPTION_ · PARAMETERS_ · EXAMPLES · BUGS
REFERENCES · HELP · SEE_ALSO

NAME

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

USAGE

polnorm input output

DESCRIPTION

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.

PARAMETERS

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?

EXAMPLES

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 

BUGS

REFERENCES

Author: Howard Bushouse, STSDAS

HELP

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

SEE ALSO

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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