sstats.sl- Calculate statistics of images
The sstats.sl script is used to calculate statistics in ACIS
or HRC images. Although in many cases it is easier (and
faster) to use the dmstat tool, this script allows you to
ignore regions of the image by using a mask file.
The script is run from within ChIPS ("ahelp chips"), as shown
in the example. To load the script:
chips> () = evalfile("sstats.sl")
This step is only necessary once per ChIPS session.
This script is used in the Calculating Statistics of Images thread.
chips> sstats( "img_stat.fits" )
Calculate statistics over the whole input image,
"img_stat.fits". The output is:
Statistics of img_stat.fits.
Mean = 1.3997e-02 RMS = 1.1977e-01 Total = 2.6730e+03
Min = 0.0000e+00 Max = 2.0000e+00 Num pixels = 190969
chips> sstats( "img_stat.fits", "emap_stat.fits" )
Repeat the above example, restricting the calculation to
just those pixels within an annulus. In this case we use
a filtered exposure map (emap_stat.fits) the same size as
img_stat.fits in which those pixels which should be
considered for the calculation have values > 0.
The output is:
Statistics of 1838_img_s3.fits[sky=region(stat.reg)] using (expmap_1.7kev_7.fits[sky=region(stat.reg)] > 0) as a mask.
Mean = 2.7784e-02 RMS = 1.6761e-01 Total = 2.6730e+03
Min = 0.0000e+00 Max = 2.0000e+00 Num pixels = 96205
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