The CIAO tools are pretty good about recording all that was done to the
file. For example I modified my evt2 file at the original resolution
and created a binned image. The commands are saved in the header file
This tells me that I selected a certain time and CCD and then applied a
GTI file to the data. I selected an energy band and a bin size of
4 for x and y. So knowing the original pixel size it is easy to
determine the pixel size of the image that you have. The last thing I
did was to trimmed the image down so that my fitting code would run
This is a nice feature of CIAO - it records and transfers information on
the file creation right in the header of the image file. There might be
an easier way to determine the resolution using CIAO, but inspecting the
header tells you exactly what was done to the evt2 file.
dmlist img4_s3a_cut.fits header | more
-- HISTORY dmcopy acism00906N000_evt2.fits[time=74161822.6840:74209200.1840, ccd_id
-- HISTORY =7:7] s3_a_evt2_f0.fits kernel=DEFAULT
-- HISTORY dmcopy s3_a_evt2_f0.fits[@lca2.gti] s3_a_evt2_f1.fits kernel=DEFAULT
-- HISTORY dmcopy s3_a_evt2_f1.fits[ccd_id=7,energy=500:7000][bin x=4,y=4] img4_s3a
-- HISTORY .fits option=IMAGE kernel=DEFAULT
-- HISTORY dmcopy img4_s3a.fits[x=3110:4510,y=3466:4866] img4_s3a_cut.fits kernel=D
On 2 Aug, email@example.com wrote:
> This question is directly about ciao, but I'm stumped.
> Is there away to find the beamsize from a fits image when it isn't in the
> normally I find it as
> COMMENT X.XX x X.XX arcsec resolution
> in the header, but I have some images that it don't have it there.
> Any ideas?
> Matt Mory
> MartNet InterNet Services 99.9% pure http://www.martnet.com
Phone: (256) 961-7664
Fax: (256) 961-7215
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