Halo artefact or something else?

Processing Deep Sky
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Tim Richter avatar
Tim Richter avatar
Hello astronomers!

I am currently working on a SHO Mosaic image in cygnus. Ha is already done, I am now moving to OIII.

This is one of the 4 OIII panels, and I am not really sure what this artefact on the bottom is. It could be from the star Sadr, which is in the panel below. 
This artefact is only in this panel (in all of the sub frames), the other panels are fine. Thus, I rule out issues with flat frames. 

Setup:
Telescope: Sharpstar 130HNT Newton
Camera: ZWO ASi 1600MM
Filter: Optolong OIII

Any ideas?
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Tony Gondola avatar
Tony Gondola avatar
A light leak or unwanted internal reflections from Sadr or a local light source would be my best guess
. I did a detail of NGC 1318 and had a visible diffraction spike from Sadr even though it was well out of the FOV. Working near a very bright star like that can have issues. I couldn't do anything about the diffraction spike but in your case, if it is an internal reflection or light leak, it should be fixable.

Can your OTA pass the daytime dark frame test?
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