Why does this have rainbow colo(u)rs on the sides?

That’s where we got some but not all of the red/green/blue filters. In these images, we collect one band at a time, so to get color images we have to take three separate exposures. At the edges, we didn’t always do this!


Wow! Thank you so much.

why not? Also, why are there different amounts of each color in different parts of the sky, , for example I can see normal color in one place, then somewhere else one color is saturated more than the others?

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The way telescope time is awarded (we had to apply for time to do this program, and it’s always highly competitive), we would get awarded a block of nights – usually 2-6 nights or half-nights in a row. We did g- and r-band during dark time (moon down) and z-band when the moon was up, so getting 3-band coverage requires good weather when that part of the sky was visible on dark and bright nights. Getting it perfect would be more trouble than it would be worth.