Good angle of an odd thing

https://www.legacysurvey.org//viewer/?ra=27.3594&dec=-72.4727&layer=galex&zoom=11

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That’s probably what’s called an “optical ghost”… when you get reflections off of filters or other optics in the telescope, some of that light can bounce back into the camera, but then because of the weird path it took, it looks like it’s coming from another direction, is out of focus, etc. Here, around the bright star in the middle you can see one big diffuse ghost, one up and to the left, and a little donut below. Those three dark spines are from the mirror support structures in the telescope, and the central hole is probably from the secondary mirror.

cheers,
dustin

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