idlastro / DAOPHOT-Type Photometry Procedures: DAOERF

[Source code]

NAME
DAOERF
PURPOSE
Calulates the intensity, and derivatives, of a 2-d Gaussian PSF
EXPLANATION
Corrects for the finite size of a pixel by integrating the Gaussian
over the size of the pixel.    Used in the IDL-DAOPHOT sequence.   
CALLING SEQUENCE
DAOERF, XIN, YIN, A, F, [ PDER ] 
INPUTS
XIN - input scalar, vector or array, giving X coordinate values
YIN - input scalar, vector or array, giving Y coordinate values, must 
        have same number of elements as XIN.
A - 5 element parameter array describing the Gaussian
        A(0) - peak intensity
        A(1) - X position of peak intensity (centroid)
        A(2) - Y position of peak intensity (centroid)
        A(3) - X sigma of the gaussian (=FWHM/2.345)         
        A(4) - Y sigma of gaussian
OUTPUTS
F - array containing value of the function at each (XIN,YIN) 
    The number of output elements in F and PDER is identical with
        the number of elements in X and Y
OPTIONAL OUTPUTS
PDER - 2 dimensional array of size (NPTS,5) giving the analytic
        derivative at each value of F with respect to each parameter A.
REVISION HISTORY
Written: W. Landsman                October, 1987
Converted to IDL V5.0   W. Landsman   September 1997