DAO_VALUE

       Returns the value of a DAOPHOT point-spread function at a set of points.

       The value of the point-spread function is the sum of a
       two-dimensional integral under a bivariate Gaussian function, and
       a value obtained by interpolation in a look-up table.  DAO_VALUE will
       optionally compute the derivatives wrt X and Y

       Result = DAO_VALUE( xx, yy, gauss, psf, [ dvdx, dvdy ] )

       XX,YY   - the real coordinates of the desired point relative
               to the centroid of the point-spread function.
       GAUSS  -  5 element vector describing the bivariate Gaussian
       GAUSS(0)- the peak height of the best-fitting Gaussian profile.
       GAUSS(1,2) - x and y offsets from the centroid of the point-spread
               function to the center of the best-fitting Gaussian.
       GAUSS(3,4) - the x and y sigmas of the best-fitting Gaussian.
       PSF  -  a NPSF by NPSF array containing the look-up table.

    RESULT - the computed value of the point-spread function at
             a position XX, YY relative to its centroid (which
             coincides with the center of the central pixel of the
             look-up table).

       DVDX,DVDY - the first derivatives of the composite point-spread
             function with respect to x and y.

       although the arguments XX,YY of the function DAO_VALUE
       are relative to the centroid of the PSF, the function RINTER which
       DAO_VALUE calls requires coordinates relative to the corner of the
       array (see code).

       DAOERF, RINTER()

       Adapted to IDL by B. Pfarr, STX, 11/17/87 from 1986 STSDAS version
       of DAOPHOT
       Converted to IDL V5.0   W. Landsman   September 1997

[Home Page] [Software, Documentation] [IDL Documentation] [Quick Reference] [Feedback]