question about astrometry and finder
Guest wrote on Jul 01, 2006
Hi Deidre,
Lindsay was working on a lot of WCS tools before she moved on to NRAO. You might take a look at the various tasks in the imcoords package. Something like mkcwcs might be what you need. There are a lot of different polynomial formalisms that astrometricians have used, so you'll have to sort out what your polynomial means. "Ideal" might imply a simple six parameter tangent plane projection - 2 degrees of freedom each for translation, scale and rotation, that is - but can usually fake it with a single scale and position angle as below.
Rob
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im> lpar mkcwcs
   wcsname = ""       WCS to create
   (wcsref = "")       WCS referencen
   (equinox = INDEF)     Equinox (years)
     (ra = INDEF)     RA (hours)
     (dec = INDEF)     DEC (degrees)
    (scale = INDEF)     Celestial pixel scale (arcsec/pix)
     (pa = 0.)       Position angle (deg)
 (lefthanded = yes)      Left-handed system?
 (projection = "tan")     Celestial projectionn
    (rapix = INDEF)     RA reference pixel
   (decpix = INDEF)     DEC reference pixel
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If I have a plate solution from an astrometry program outside of IRAF, is there some way to put this info into the header of an image so that I can have RA,DEC readout in ximtool? Phil gave me an astrometry fortran program a long time ago. It produces a polynomial of ideal plate X,Y in radians as a function of measured X and Y. Thanks.
Lindsay was working on a lot of WCS tools before she moved on to NRAO. You might take a look at the various tasks in the imcoords package. Something like mkcwcs might be what you need. There are a lot of different polynomial formalisms that astrometricians have used, so you'll have to sort out what your polynomial means. "Ideal" might imply a simple six parameter tangent plane projection - 2 degrees of freedom each for translation, scale and rotation, that is - but can usually fake it with a single scale and position angle as below.
Rob
------
im> lpar mkcwcs
   wcsname = ""       WCS to create
   (wcsref = "")       WCS referencen
   (equinox = INDEF)     Equinox (years)
     (ra = INDEF)     RA (hours)
     (dec = INDEF)     DEC (degrees)
    (scale = INDEF)     Celestial pixel scale (arcsec/pix)
     (pa = 0.)       Position angle (deg)
 (lefthanded = yes)      Left-handed system?
 (projection = "tan")     Celestial projectionn
    (rapix = INDEF)     RA reference pixel
   (decpix = INDEF)     DEC reference pixel
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Last post on Jul 01, 2006