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imagepol.imagepoltestimage - Function
1.1.4 Attach the Imagepol tool to a test image file
Description
This function can be used to generate a test image and then attach the
Imagepol tool to it.
The test image is 4-dimensional (RA, DEC, Stokes and Frequency). The Stokes axis holds I,Q,U and V. The source is just a constant I (if you don’t add noise all spatial pixels will be identical) and V. Q and U vary with frequency according to the specified Rotation Measure components (no attempt to handle bandwidth smearing within channels is made). The actual values of I,Q,U, and V are chosen arbitrarily otherwise (could be added as arguments if desired).
You can use this image, in particular, to explore the Rotation Measure algorithms in functions rotationmeasure and fourierrotationmeasure.
If you don’t specify the Rotation Measure, then it is chosen for you so that there is no position angle ambiguity between adjacent channels (the value will be sent to the Logger).
The noise added to the image is specified as a fraction of the total intensity (constant). Gaussian noise with a standard deviation of sigma * Imax is then added to the image.
Arguments
Inputs |
| ||
outfile |
| Output image file name
| |
| allowed: | string |
|
| Default: | imagepol.iquv |
|
rm |
| Rotation Measure (rad/m/m). Default is auto
no-ambiguity determine.
| |
| allowed: | doubleArray |
|
| Default: | 0.0 |
|
pa0 |
| Position angle (degrees) at zero wavelength
| |
| allowed: | double | |
| Default: | 0.0 |
|
sigma |
| Fractional noise level
| |
| allowed: | double | |
| Default: | 0.01 |
|
nx |
| Shape of image in x direction
| |
| allowed: | int |
|
| Default: | 32 |
|
ny |
| Shape of image in y direction
| |
| allowed: | int |
|
| Default: | 32 |
|
nf |
| Shape of image in frequency direction
| |
| allowed: | int |
|
| Default: | 32 |
|
f0 |
| Reference frequency (Hz)
| |
| allowed: | double |
|
| Default: | 1.4e9 |
|
bw |
| Bandwidth (Hz)
| |
| allowed: | double |
|
| Default: | 128.0e6 |
|
bool
Example
"""
#
print "\t----\t imagepoltestimage Ex 1 \t----"
po.imagepoltestimage(outfile=’imagepoltestimage’, rm=200)
po.rotationmeasure(rm=’rm.out’,rmmax=250)
ia.open(’rm.out’)
ia.statistics()
#viewer()
#
"""
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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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