Strange Integration Behavior

[Buzz]

I am doing a LRGB/Ha/S2/O3 image and used the preprocessing script to calibrate and register the files.
When I came to integrate the S2 files, the high rejection map (attached) suggested misaligned stars and the integrated image had streaks in the same direction. Using Blink on the registered files shows perfect alignment on all frames. I purged the files and started again, with the same result. None of the other stacks had this issue. I tried the process again, using StarAlignment on the calibrated files, but with no difference.
Any ideas? (build 1352 on Mac.) It seems to be getting confused.

[RickS]

The rejection map doesn't look especially odd.  Do you have some hot pixels and some drift between subs?  I'd do a Blink zoomed in on one of the areas of concern and see what you can see.  You might want to try adding CosmeticCorrection to your BPP run if the problem is hot pixels.

[Buzz]

RickS - thanks, I do not think the tracking is the issue, otherwise I would see it on the other channels? (guided Paramount MX). I do have a CC map as part of the calibration - maybe not aggressive enough - I need to post a portion of the integrated image - it shows diagonal smears. I went back to first principles on the calibraton, registration and integration and no change. The SII channel is the noisiest and it could just be that the rejection settings are not severe enough or maybe the registration is getting confused by hot pixels (though I had filter enabled in Star Alignment). It is a puzzle this one.

[pointofview_365]

I'm by far an expert here, but I have run into this same problem twice with this update. If I remember correctly, I chose a different reference image, and even a different channel to star align everything too(choosing the best Ha frame of the lot). the Sii data refused to stack properly like the rest of the other channels. Just a couple of weeks ago, I couldn't get the Blue channel to stack right but the others where fine. I got it to work star aligning everything to Lum.

[Buzz]

Hi - I think I finally cracked it - the SII was a lot noisier and far more susceptible to CCD noise. The registration did have a few oddballs, but after tweaking the sensitivity, I got it to behave. The trails were actually remaining warm pixels, not removed by the cosmetic correction. The streaking in my image was actually residual dark noise (optimize was on), which was displaced between exposures.  I fixed it with a revised calibration setting and a dose of noise reduction. (And this was with 50 20-minute exposures too)
The image came out alright in the end. This is a first draft.

[Buzz]

[update] -  the previous image was a bit of a fudge - with a lot of smoothing on SII. I realised that my master dark/bias were out of date and repeated them. I started from the beginning again (with CC too) and the SII stack is much cleaner without striations and the stuttered rejections (above) also disappeared, with modest SD rejection values of 4/3. In this case I did all the registrations outside of the BPP script and ensured it was not picking up on any hot pixels. It will take me a day to run through it all again and come up with the final image. The stacks already look more promising so here's hoping.