Automated photometry question

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Automated photometry question

Post by RJN » Tue Aug 24, 2004 3:13 pm

Lior's WOLF program that does the automated photometry on NSL FITS images is really fantantic and a tremendous achievement. Still, however, it sometimes does things that I do not understand. Here is one example:

Sometimes the (C25-B) number (for example), is higher than the (C16-B) number. This happens several times, for example, in the photometry file for Polaris (Alpha Umi) listed here:
For example in the first line of photometry.

Could you explain again how this could happen?

Definition of terms (for those following along who don't know): B means Background: C16 is the sum of the top 16 pixels, divided by 16. Likewise, C25 is the sum of the highest 25 pixels divided by 25.