[Kstars-devel] CCD focusing

[Dirk Huenniger]

>>Yes, I was just writing basically the same thing :).  Does the FITSViewer
>>already have a FWHM function?
>>    
>>
>
>No it doesn't write now, but it would be great to include such function in it!
>
>  
>
I think calculating a good FWHM is rather not trivial. You first have to
select suitable stars and than you have to do a two dimensional fit.
There allready is a gnu programm called  sextractor which takes a
fitsfile classifies the objects and writes the FWHM of each object in an
ascii file. Doing a median on that data I got reasonable estimates for
the FWHM. I think it would be a good idea to use such a mechanism,
instead of developing own code for that.

just install sextractor
than download /daofind.param default.sex and default.conv/
from http://tdc-www.harvard.edu/software/wcstools/sextractor/
add the line FWHM_WORLD to /daofind.param/ at the end.
than run sextractor image.fits
there will be an ascii file called test.cat. In the fourth column you
will find the FWHM

Cheers Dirk