SharpCap Forums

Hello:
i make life stack with SharpCap (registered version), and the other day with Thor´s Helmet, I was comparing two images, (one 4 february,34 minutes, and other in day 22, 50 minutes).
I see a possible flare or similar, and now i am searching for images from this time, to confirm or not ( no luck for now).
The image is between 21:30 and 22:30 TU, ngc2361/ngc 2359, from Spain, with a Skywatcher ed80, a svbony sv220 filter, reducer and imx585 camera.
Maybe it was only and artifact from stacking or camera?. I use live Stack without another options, no improvements, no darks, flats,. only dither directly (without tube).
I upload the two images...
Thanks.

Hi,

I can make some suggestions, but can't be sure about the cause. A few things that should be considered include

1) A secondary image of a nearby bright star caused by reflections inside the telescope (edges of lenses, etc). There looks like there is a slight difference of rotation between the two images, which might explain why something like that could show up on one but not the other

2) One or more frames in the stack might have been mis-aligned - that might put - for instance - a faint copy of the bright star in the lower right into the image in another position. If that was the case though I'd expect to see duplicates of some of the other brigher stars show up, which I don't see.

3) Something real at that location in the sky

If you have saved the raw frames while live stacking then it may be worth checking those to see if the extra star shows up in the individual images. Even if you haven't saved those images, there should be a 'stacklog.csv' file alongside the saved images (at least for recent versions of SharpCap). That file contains the calculated X and Y offsets of each frame along with the rotation. If there are a few frames where the offsets or rotations are much larger than the others then it could be option 2 - the mis-aligned frames in the stack.

Hope this helps,

Robin

Thanks Robin:

I usually don´t save raw images, only "save exactly as seen" the image, with histogram and color adjusts, and the .txt archive generated; I think have a "raw" save, when closing the session (must check for .csv).

The first image is 4-februrary, and the second (with "anomaly") is from 22-february, I changed the mount, from old heq5 onstep to a SW eq6-r, maybe this explain the small difference in rotation/position, since i made a new alignment.

When live stacking I save (what i see) every 10 or 15 minutes, the image i posted here is the last, with 52 minutes, I upload the first image from this night, when it was only 15 minutes of stack,.. the "anomaly" is there.

I made some shots 2 or 3 days before of the Thor´s Helmet, and another try the day after (23), and there is no "anomaly" for sure in this moments.

Maybe i can find some image from others at this time, to make sure....but, its good to see and search for other explanations.