PhotoRed Reduction Routines - Transforms Errors
The errors routine allows you to check the transforms by converting the instrumental
magnitude of each star in a standard field to a standard magnitudes and then subtracting
the catalog value for the star, assuming the same band for both the instrumental and
standard magnitude. In a perfect world, the mean error would be 0 and the standard
deviation would be the same. However, there is always some random scatter in the data.
This routine shows you just how much and if there might be a systematic error, e.g., the
redder the star the greater the error in a given filter.