[gnuastro-devel] [task #14421] Make PSF profiles without catalog

[Mohammad Akhlaghi]

URL:
  <http://savannah.gnu.org/task/?14421>

                 Summary: Make PSF profiles without catalog
                 Project: GNU Astronomy Utilities
            Submitted by: makhlaghi
            Submitted on: Sat 25 Mar 2017 12:28:15 AM JST
         Should Start On: Sat 25 Mar 2017 12:00:00 AM JST
   Should be Finished on: Sat 25 Mar 2017 12:00:00 AM JST
                Category: MakeProfiles
                Priority: 5 - Normal
              Item Group: Enhancement
                  Status: Postponed
                 Privacy: Public
        Percent Complete: 0%
             Assigned to: None
             Open/Closed: Open
         Discussion Lock: Any
                  Effort: 0.00

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Details:

Currently MakeProfiles needs a catalog as input for profile parameters, the
reason is that multiple parameters are needed to define a generic profile.

But a PSF, or convolution kernel, isn't a generic profile and is highly
constrained: for example its center is fixed (the center of the central
pixel), the image size is also dependent on the truncation radius, and its
total sum of values has to be one. So, the only parameters necessary are the
radial function, its FWHM, and its truncation radius.

Making a kernel (for convolution) is necessary for several Gnuastro programs
and it is inconvenient to make a catalog every time you need a single kernel.
So we can add an option (called `--kernel' maybe) to MakeProfiles to only make
one PSF with a command like this:


$ astmkprof --kernel=gaussian,3,5       # FWHM, Truncation
$ astmkprof --kernel=moffat,3,2.8,5     # FWHM, Beta, Truncation


With this feature the current behavior (where Gaussian and Moffat profiles get
built individually and not on the merged image along with the Sersic profiles
for example) can be removed.

Please share your thoughts if you have any ideas to make this better before it
is implemented.




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