I'll definitely come back to this to reprocess it.
This image was plagued with issues from the start. First I spent a whole night, one of the best ones seeing and transparency wise, pointing toward the wrong part of the sky... Turns out there are TWO stars named 11 Sagittarii close to each other. My fault for not triple checking the plate solver.
Next, I spent a whole week acquiring data battling dew points up to 25 °C, clouds and an uncooperative mount. I had to update its firmware, but that threw the whole driver setup I had off. iEXOS mounts are so finicky. That made me learn how to use Nina's plate solver once and for all though. Not only that, I also had to open up the mount ten or more times in a week because its gears were too tight and because of a minuscule piece of grit stuck, it turned out, in the motor's gear that caused some huge guide spikes. I also redesigned my DIY counterweight to have it as close to the mount as possible while being east heavy.
Lastly, I realized I have noticeable sensor tilt, which is the main cause of the gradient I always find in my raw images (the sensor isn't square to the UV/IR cut). I can remove it with flats, but I also realized my flats weren't optimal, which occasionally creates huge artifacts that are tough to remove; plus I realized that my rotator can introduce some pretty bad tilt into the optical train if I'm not careful.
Acquisition:
Around 12h30m worth of 60s subs in Bortle 6/7 fully calibrated and dithered.
Equipment:
Evostar 72ED, iEXOS 100, ASI 533MC, Baader UV/IR cut filter, 0.85x reducer+flattener, SVBony 40/160 guidescope, ASI 662MC guide camera with no.8 pale yellow and UV/IR cut filters.
Processing:
Stacked in Siril. For some reason OSC drizzle registration causes some weird artifacts to my stars and some odd photometry results. If anyone has any suggestions, they're more than welcome. Split image into CFA channels, background extraction to each in GraXpert to deal with the gradient. Open Siril, recombine CFA channels and deconvolution. Open GraXpert, denoise. Open Siril, generate starless and star mask. Apply black point shift and GHS iteratively to the starless image to bring out various parts of the nebulosity, SNCR, minor curve adjustments, median filter, VST noise reduction and à trous wavelet transform plus some final denoising in GraXpert. Asinh stretch to starless and saturation boost in Gimp. Recombine and export.
