Problem:

This image, which consists of a 2x2 mosaic of images read out by 4 amplifiers, has multiple problems, none of which are easily fixable:

1. Fixed pattern noise. This noise is visible throughout the bottom two quadrants as a wavy pattern (low frequency component), and as a white stripe toward the bottom half of the top two and bottom two quadrants (high frequency component; harder to see in this image).
2. A reflected ghost image of the bright star (HD100546) in the bottom left quadrant.
3. 3 ghost images of the same star, visible as small rings or doughnuts in the quadrants not containing the star itself. These are created by amplifier cross talk, ie., electronic interference between the 4 amplifiers.
4. A stripe between the bottom and top half of the image.
5. Dark blotches of unknown origin throughout the middle part of the image.

Fix:

None of the problems are easily fixable. Problems 1 and 3 are due to the electronics of the setup and may not be fixable at all. Problem 2 is a reflection problem, the origins of which are usually not easy to track down and eliminate. It is not clear what caused problems 4 and 5.