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What are these strange reflections?

Acquisition OIII Deep Sky Artifacts
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Willem Jan Drijfhout avatar
Willem Jan Drijfhout avatar
Does anyone have an idea what these strange 'donuts' are in the image? It appears a symmetrical pattern of three donuts on each side of the frame, with the center of the three a bit brighter than the ones at the edges. They look like some kind of a reflection of the center star? They are only in the OIII and Ha images, not in any RGB images of similar exposure length, but keep in mind that the NB images are taken at high gain, vs the RGB at low gain.
Any insights appreciated.

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GalacticRAVE avatar
GalacticRAVE avatar
These are reflections/refraction of the central bright object on the microlens array on the chip of your camera. There is quite a bit of discussion on this in cloudy nights, look on particular for conctributions by Mark Shelly (e.g. thread # 12 on https://www.cloudynights.com/topic/635937-microlens-diffraction-effect-explained/)

Matthias
Willem Jan Drijfhout avatar
Willem Jan Drijfhout avatar
Thank you Matthias, I had not seen that before. In that case, it looks like there is not much one can do about it, other than dealing with it in post-production.
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