Mysterious artifact I can't explain, curious as to what it might be Other · David Koslicki · ... · 5 · 628 · 8

Recently, I've been imaging vdB 132 and the surrounding region and noticed what I first thought was a sensor issue, but the more I think about it, the less I can explain it. Namely, there is this odd repeating dot structure on the very edge of my sensor:

Sensor is rotated by 0.36 degrees, so basically north is up.

It isn't fixed in place, as it moves along with the dithering. The following GIF is of frames taken in time order, and the artifact is in the upper right (flipped vert & horiz to the above):

Looking at this region in Stellarium, I expected to see some bright star just out of frame, perhaps reflecting off of the filter, but there doesn't appear to be anything interesting nearby:

It also shows up most strongly with my RGB (Zwo) filters, and faintly in Ha (Baader). I could be convinced that it's some sort of reflection (as the repeated dot pattern overlaps with a single star as it moves out of the frame. But this wouldn't explain why only that single faint star is reflecting off something in my imaging train, in the exact same location in space, over two nights, and with different filters and brands.

Here are the stacked (maximum) and cropped images of Ha, R, G, B respectively:





You can see that over the two nights I imaged, this artifact shifted slightly.

And in RGB to see the color is different from surrounding stars:



ASTAP doesn't recognize it as an asteroid or comet (which would've been weird as it doesn't move consistently in time). Looking at other frames I've taken of different regions of the sky, I have not seen this artifact before.

Anyone have any ideas?

Thanks @abreen ! Next time the clouds clear, I'll try rotating the OTA and sensor and see if this still happens. Back of the envelope calculation says that my ~6inch dew shield isn't nearly long enough to block out Vega, so that might very well be it! Still funny it's happening on the extreme edge of the sensor *shrug*

@David Koslicki were you able to solve the mystery?