Fwd: ellipticity and position angle

Francisco Valdes wrote on Nov 14, 2005

From: Philip Massey <massey@lowell.edu ([email]massey@lowell.edu[/email])>
Date: November 14, 2005 1:02:07 PM MST
To: Frank Valdes <valdes@noao.edu ([email]valdes@noao.edu[/email])>
Subject: Re: ellipticity and position angle

Thanks for pointing me at this.  I actually just threw up my hands and wrote my own little FORTRAN code, whichwas fine, but this is good to remember for the future.

thanks,
phil

On Nov 14, 2005, at 12:53 PM, Frank Valdes wrote:

Hi Phil,
Unless you want me to put together a reply on IMEXAM I suggest you look at the task PSFMEASURE.  In the current version of IRAF it is part of the OBSUTIL package.  To do the non-interactive job you want you would make a text file of x/y for all your stars. 

ob> psfmeasure starfield imagecur=mystars.dat >G dev$null
** Select stars to measure with 'm' and finish with 'q'.
** Additional options are '?', 'g', and :show.
NOAO/IRAF V2.12.2a-EXPORT valdes@tucana.tuc.noao.edu ([email]valdes@tucana.tuc.noao.edu[/email]) Mon 12:47:40 14-Nov-2005

          Image  Column    Line     Mag    FWHM   Ellip      PA SAT
      starfield  164.79  184.59    0.00   2.206    0.06     -23

  Full width at half maximum (FWHM) of 2.2061

This is with the default parameters.  Note the redirection of the graphics to null file.  You could redirect the graphics to a metacode file viewable with (e.g.) GKIMOSAIC.  However for 30,000 stars I don't think you want that.

Let me know if you have questions or if you prefer to use IMEXAM.  The algorithms in PSFMEASURE are largely the same as in IMEXAM.

Yours,
Frank

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Last post on Nov 14, 2005