Uneven detection threshold in HAP catalogs

[stscijgbot-hstdp]

Issue HLA-1407 was created on JIRA by Rick White:

When there are shifts between images that result in uneven exposure times across the image, the HAP segment and point catalogs both look incorrect.

The HAP segment catalogs appear to use a deeper detection threshold on the edges than in the center of the images, where there are more exposures. The opposite ought to be true: since the exposure time is greater in the center, there should be more sources detected there.

On the other hand, the HAP point catalogs have no sources at all in the edge regions. The point catalogs only include sources in the region where all the exposures overlap.

A test confirms that the problem still exists in the current version of the HAP pipeline.

There must be one or more bugs in the calculation of the noise in different image regions. And apparently the point catalog only finds sources in a restricted region.