The challenging supernova remnant CTB-1 (Abell 85; LBN576) and nearby brighter nebulae Sh2-168 and Sh2-169, along with open clusters NGC 7788, NGC 7790.

CTB-1 is estimated to be 10,000 light-years distant and 100 light-years in diameter.

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Imaged on:

August 28th, 2019 SQM 20.39 29C calm; Lum, Ha and OIII

30th, SQM 20.64 23C breezes; Ha

31st, SQM 20.36-20.75 24C-15C calm; OIII

November 9th, SQM 20.55 11C calm; Ha, OIII

10th, SQM 20.61 10C calm; Ha, Ha+OIII(duo filter), Lum

Sensor cooling was 0C to -10C in August and -10C to -20C in November.

In the case of all OIII integration times listed, the actual wall clock time was a third as long as indicated, because I stacked the OSC's Bayer matrix g1, g2 and b subarrays into a single deeper integration, to boost SNR at the expense of resolution. Of course for Ha, I retained and stacked only the Bayer r subarray data.

It did not help any that I was also double-filtering the signal by imaging narrow band on a Bayer sensor, but estimated that this camera's QE and low noise performance was the best in my kit despite that.

L 62x30sec (for RGB stars)

Ha 120x180sec

OIII 118x300sec

OIII 62x600sec

STC Duo Ha+OIII 48x180sec

All channels were drizzle integrated at 2x for post processing then cropped and down-sampled to standard UHD format.

An RGB stack of short exposure unsaturated stars was treated as a separate workflow and non-star content was crushed into black levels. All narrow band stacks were processed with the beta release of StarNet++ in PixInsight to remove the stars in a separate workflow; then these layers were blended in PixelMath for the final rendering, with both PI and Affinity Photo used for noise reduction.

Corresponding library master bias, dark and flat frames were applied.

All bias frames were noise-reduced 5-layer PI superbias formatted. I used PI's MLT process to noise reduce all master flat frames.

Unguided mount tracking at King rate.