ellipticity and position angle
Francisco Valdes wrote on Nov 14, 2005
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.Â
ob> psfmeasure starfield imagecur=mystars.dat >G dev$null
** Select stars to measure with 'm' and finish with 'q'.
** Additional options are '?', 'g', and :show.
NOAO/IRAF V2.12.2a-EXPORT valdes@tucana.tuc.noao.edu ([email]valdes@tucana.tuc.noao.edu[/email]) Mon 12:47:40 14-Nov-2005
     Image Column  Line   Mag  FWHM  Ellip   PA SAT
   starfield 164.79 184.59  0.00  2.206  0.06   -23
 Full width at half maximum (FWHM) of 2.2061
This is with the default parameters. Note the redirection of the graphics to null file. You could redirect the graphics to a metacode file viewable with (e.g.) GKIMOSAIC. However for 30,000 stars I don't think you want that.
Let me know if you have questions or if you prefer to use IMEXAM. The algorithms in PSFMEASURE are largely the same as in IMEXAM.
Yours,
Frank
On Nov 7, 2005, at 9:36 AM, Philip Massey wrote:
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Unless you want me to put together a reply on IMEXAM I suggest you look at the task PSFMEASURE. In the current version of IRAF it is part of the OBSUTIL package. To do the non-interactive job you want you would make a text file of x/y for all your stars.Â
ob> psfmeasure starfield imagecur=mystars.dat >G dev$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
On Nov 7, 2005, at 9:36 AM, Philip Massey wrote:
I have a (long) list of x and y positions of stars in an image, and would very much like to know the
ellipticity and position angles of the images: most are stars, but a few are spurious detections on
defraction spikes.
I know that imexamine's "a" key will give me what I need, but I have been unable to figure out how from
the help page how to feed imexamine a list of coordinates and have it do an "a" on them. It seems like
it is set up for this (defkey='a' by default!).
How can I do this without doing it interactively, and/or are there other tasks that would give me this
information?
thanks,
phil
Begin forwarded message:
From: Philip Massey <massey@lowell.edu ([email]massey@lowell.edu[/email])>
Date: November 7, 2005 10:05:10 AM MST
To: fvaldes@noao.edu ([email]fvaldes@noao.edu[/email])
Subject: imexamine
Hi, Frank---
Sorry to bother you but I think this will be a quick question.
"imexamine" clearly is intended to have the ability to apply a default key (by default, "a") to a cursor xy
input list.  But, I've had miserable luck with this. What I'd like to do is get the values for the
ellipticities and position angles for about 30,000 xy positions on an image. I thought I could do this
by
setimcur="text"
unlearn imexamine
imexamine M31F2Vm.fits use_dis-
but for some reason that doesn't seem to work.
thanks,
phil
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Last post on Nov 14, 2005