Last night I took around 200 15s photos over 2 hours with a Dwarf 3 towards the current 3i Atlas position and this morning I see this in the stacked result. I just don't know if it's 3i or not. It doesn't look like what i've seen in other photos. I assume the apparent elongation is due to the stacking process making the stars fixed with the comet moving. Any conjectures?
I think it is. The comet is moving while the Stars Are fixed. In Order to get the comet you need to process the comet and the backgrpund separatly. Just Look it up on yt, I am sure there are plenty of Tutorials.
Yes I agree. But what do you think caused the individual bright segments? I see at least two. I'm thinking perhaps a cloud passed by and dimmed some images so I will look at the individual photos.
Did you have a Pause in your Session ?
Not at all.
Then it is atmospheric, like you said - Clouds.
Yes, I'm going to check my individual FITS. It will take forever.
Just every 5-10 should be enough
Good point
This looks more like an edge-on galaxy to me. 3I is currently around the Virgo-Leo border which is FULL of galaxies.
I would upload your image here and see what it pops out: https://nova.astrometry.net/upload
Edit: I'm not awake and didn't realize you already did that.
Still looks like a galaxy IMO. Maybe try putting the ephemerides into Stellarium and see if it passed by those stars when you were imaging.
That's exactly what I did and the photo I posted is from nova processing. If it's a galaxy nova missed it.
Yeah, I edited my comment 😅
It may indeed be the comet, but it looks almost too mottled to me, and I would still expect to see a bit of a tail.
See my edit for another suggestion to check.
I'm glad to see your suggestions because they're exactly what I've done so I haven't missed anything :) I spent a couple of hours with stellarium and nova this morning matching stars until it started driving me crazy :)
I have to get back to basics. I really think it's a streaked stacked comet interrupted by passing clouds. I'm going to process substacks until I find the culprit.
Update. I looked through the time tags of my close to 600 images and found a 10 minute gap after about an hour. I was sure this is when clouds came over so I only processed the images before the gap with Siril, about 150. I looked at the result fully expecting the gap to be gone but it was still there, one of the two anyway. At this point I'm just going to assume it was an unknown data artefact and move on. It's not the best telescope anyway. If anyone wants to do their own analysis I will gladly send you all the 600 FITS. This comet has enough crazy speculation without me adding to it. Thanks for all the suggestions!
Download Stellarium , Import the comet , and verify the Position .
I've used Stellarium but don't know how to import the comet position. I'll look that up.
This is consistent with a comet but I'm not sure.
There's a Siril tutorial for comet processing (some steps are superfluous), you can try that to see if it gives a better picture of the comet:
https://siril.org/tutorials/comet/
I've done that with other comets using DSS and it's extremely laborious. I'd have to go through each of 600 images and tell it where the comet is. It's not that important to me, I'm just glad I got something.
With Siril you point the comet on two frames (one near the begin, one near the end) and it extrapolates the others. I'll be curious to see the result with the tracked comet but that's your call :)
Oh I didn't know that, I've used siril on stars but I've only used deep space stacker for comets. I'll try it!
The fuzzy streak is consistent with a Stellarium ephemeris plot of the comet's position between 8:45 and 11:05 UT on Dec 18.
Thanks! That's when I shot it. Interestingly, the usual photo of 3i is a fuzzy ball. That's because the binaries are stacked on top of each other. I could have done that but it's a time consuming PITA. Instead I chose to fix the stars and let the comet look streaky from its motion. But I was thinking, if a comet is varying in brightness from clouds or anything, the stacked photo on the comet will not detect it. Only a streaked photo will.