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NRAO Home > CASA > CASA Toolkit Reference Manual |
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imagepol.depolratio - Function
1.1.4 Linear depolarization ratio
Description
This function returns the linear depolarization ratio computed from two
frequencies; this is the ratio of the fractional linear polarization at the two
frequencies. Generally this is done when you have generated two images, each
at a different frequency (continuum work). Thus if the fractional linear
polarization images are mν1 and mν2 then the depolarization ratio is mν1∕mν2.
This function operates with two images; the first (at frequency ν1) is the one attached to your Imagepol tool. The second (at frequency ν2) is supplied via the argument infile, which is a String holding the name of the image file.
In generating the depolarization ratio, you may optionally debias the linearly polarized intensity. This requires the standard deviation of the thermal noise. You can either supply it if you know it, or it will be worked out for you with outliers from the mean clipped at the specified level.
You can get the depolarization ratio error image with function sigmadepolratio.
Arguments
Inputs |
| ||
infile |
| Other image
| |
| allowed: | string |
|
| Default: |
| |
debias |
| Debias the linearly polarized intensity ?
| |
| allowed: | bool | |
| Default: | false |
|
clip |
| Clip level for auto-sigma determination
| |
| allowed: | double |
|
| Default: | 10.0 |
|
sigma |
| Standard deviation of thermal noise. Default is auto
determined.
| |
| allowed: | double |
|
| Default: | -1 |
|
outfile |
| Output image file name. Default is unset.
| |
| allowed: | string |
|
| Default: |
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image
Example
"""
#
#print "\t----\t depolratio Ex 1 \t----"
#po.open(’stokes.4800’)
#dpr = po.depolratio(infile=’stokes.8300’) # m_4800 / m_8300
#edpr = po.sigmadepolratio(infile=’stokes.8300’);
#dpr.done()
#edpr.done()
#
"""
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Copyright © 2016 Associated Universities Inc., Washington, D.C.
This code is available under the terms of the GNU General Public Lincense
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