DAOPHOT-type Photometry                                  June 2000

  These are a set of IDL procedures adapted from an early FORTRAN
  version of DAOPHOT aperture photometry.   The creators of DAOPHOT
  have no responsibility whatsoever for the IDL code.  The IDL code
  will give similar, but not identical, results as the original FORTRAN.
  A slight modification of the procedures for use with digitized 
  photographs is available from the UIT (Ultraviolet Imaging Telescope) group. 
  A LaTex file daophot.tex  in /text supplies further documentation for 
  the IDL-DAOPHOT procedures for CCD images.


  In May 1996, the following updates were made to the code
       (1) Non-standard system variables are no longer used.   The PRINT 
           keyword is used instead of !TEXTOUT, and the DEBUG keyword is used
           instead of !DEBUG.
       (2) The T_* procedures now request the *name* of a disk FITS ASCII table
           for storing the input and output results.  
       (3) NSTAR now has a /VARSKY keyword to allow the skylevel to vary.

 In July 1997, the procedures were modified so that the PSF residuals are
 written to a FITS file, rather than a STSDAS file.    To convert a PSF 
 file 'psfname' created earlier in STSDAS format, use the following commands:
	IDL> sxopen,1,'psfname',h
	IDL> psf = sxread(1)
	IDL> writefits,'psfname.fits',psf,h 

 In June 2000, the procedure aper.pro was modified to allow it to compute the
 exact area of the intersection of a circle with square pixels.