I investigated diff_id 65024, skycell 1383.111 to find out some of the causes of the false Mops Detections.

The following is a rough count of the different classifications of detections:

type	number
burntool	49
cosmic ray	20
star wing	88
star core	37
round	40

"round" refers to objects which appear generally psf-like in the diff image (round and subtending more than a pixel or 2). Most, when investigated further, are small cosmic rays which are convolved into something extended, but probably a bit smaller than the convolved PSF. (Edit EAM to further clarify 'round')

Here are some examples from each of the categories.

Burntool

There are 4 detections on this burn.

Cosmic ray hit

There are 2 cosmic rays here, each resulting in a detection.

Star wings

2 bright stars, the wings are detected (also, a burntool in the far right)

Star cores

These are subtractions that are not quite lined up.

"OK"

Sometimes these are real, most of the time these are actually not real (if you look at the warps).