GPC1 Defects

Here is an example of a small (nearly single pixel) type of defect which appears in GPC1 images but is not in our masking.

The two images are a y-band TTI image pair taken 10s of minutes apart with nearly, but not quite, the same pointing. The chip-pixel coordinates for stars differ by about 3 pixels.

The images show 3 'objects' in a triangle, and another faint object with somewhat fuzzier, larger shape. The last object is a real PSF, and like other stars has the same celestial coordinates between the two images to 1 pixel, but chip coordinates are off by 3 pixels. The other three objects are some kind of defect: they have the same chip pixels coordinates to better than a pixel, but differ on the sky by 3 pixels.