A Comparative Test of CCD Reduction Procedures

Three data reduction methods, applicable to time-resolved CCD photometry
of open clusters, are described. A sample set of images is reduced
independently by three people, using various approaches, and the results
are compared. The test reveals systematic differences in the FWHM and
magnitudes produced by the different software. The reduction package
MOMF and pure aperture photometry are found to be equivalent in
precision, but the results obtained with these methods should not be
merged when high precision is required.