HOW-TO Obtain PSF information of science images¶
A simple recipe is available to make several plots of SExtractor parameters
relevant to the PSF. The recipe is
$AWEPIPE/astro/filerecipes/PSF_Anistropy.py and is used as follows:
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CATEGORY : Health check
PURPOSE : Detect PSF Anisotropy
FULFILLS : Requirement 554 (Category III)
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This recipe makes 5 plots of SExtractor parameters:
1) Bars of length FWHM_IMAGE (times a scale factor) and angle w.r.t.
x-axis Theta. Average FWHM_IMAGE and THETA are evaluated per area
in a grid of Xpos/Ypos.
2) MAG_ISO vs. FLUX_RADIUS (half-light radius)
3) FWHM_IMAGE vs. THETA (position angle)
4) FWHM_IMAGE vs. Xpos-CRPIX1
5) FWHM_IMAGE vs. Ypos-CRPIX2
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Mandatory inputs :
-l : list of input split raw or processed science images
Configuration parameters (min - [default] - max) :
-s : switch to not run SExtractor (if catalogs already exist)
-d : SExtractor detection threshold
range: 0.0 - [10.0] - 100.0
-f : maximum FLAG of sources
range: 0 - [0] - 255
-m : maximum FLUX_MAX of sources
range: 0 - [60000] - 70000
-r : minimum FLUX_RADIUS of sources
range: 0.0 - [0.0] - 50.0
-rm : maximum FLUX_RADIUS of sources
range: 0.0 - [50.0] - 50.0
Switches :
-in : interactive mode (if omitted a postscript file is created)
Example of use :
awe PSF_Anisotropy.py -l image12345_?.fits [-s] [-d 5.0] [-f 1]
[-m 50000] [-r 2.0] [-rm 5.0] [-in]
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Note that the recipe can be used on a single coadded image by giving it as input.
Below is an example of an output plot
Example output plot of PSF_Anistropy
