Description (wikipedia)Sh2 -91 is a tenuous
emission nebula visible in
the constellation Cygnus .The cloud is located about 1 ° north of the famous
double optic Albireo , a third
magnitude star visible also from urban centers; despite its large size, Sh2-91 is very weak and its observation is extremely difficult, as well as its photographic recovery, which can be done through the use of special filters. The best time for its observation in the evening sky is from June to December, especially from the boreal regions.Sh2-91 constitutes the southern and most extensive filament
of the supernova remnant G65.2 + 5.7 , located about 800
parsecs (2600
light years ) from
the solar system in a galactic region rich in dense
molecular clouds , on which the great
fissure of the Swan ; G65.2 + 5.7 is in fact a
super bubble extended by about 180 parsecs and placed 80 parsecs north of
the galactic plane .
[3] Sh2-91 shows a strong
polarization , indicating the presence of a strong
magnetic field .
[2] [3]Personal noteTrying out mosaic work with a 2 panel image of this not so often targeted object. Integration went well and I noticed that making sure the original panels are well calibrated and flattened makes it easier to control the quality later on. It also helps to "hide" the seam between the panels. Still struggling a bit with blotchiness of the colors (especially red). When I try to sharpen the synth Lum this noise appears in the nebula. When trying to get rid of it, I lose detail ;-(
Workflow2 panel mosaic, 5 hrs integration time per panel per filter; 30 hr in total.
Pixinsight: WBPP, Drizzleintegration of each master, DynamicCrop, EZdenoise, DBE.
Luminance: Syntethic Luminance from SHO, EZDenoise, MaskedStretch, Histogram transformation, Starnet2, MLT denoise, range mask, HDR-MT, LocalHistogramEqalization, StarReduction
Chrominance: SHO combination, EZDenoise, MaskedStretchm ArcSinhStratch, Starnet2, MLT denoise, Curves to boost the colors, StarReduction
Please let me know your feedback and your suggestions on how to improve further. Thank you! 
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