Fleming's Triangle (Pickering's Triangle)

This is the third part of the Cygnus Loop that I have imaged.  The wispy clouds of hot gas and dust that make up this emission nebula are the result of a massive supernova explosion that occurred 5000 to 8000 years ago approximately 1500 light-years away in the constellation Cygnus.  I have imaged Eastern Veil and Western Veil (Witches Broom), brightest and most popular parts of the Cygnus Loop, already and decided to try my luck with Fleming's Triangle (a.k.a. Pickering's Triangle) this time.  It was discovered photographically in 1904 by Williamina Fleming at Harvard Observatory and originally named after Edward Charles Pickering who was director at the time.

I really love the wispy fibrous appearance of this whole area.  I spent some pre-imaging time planning to frame it as I did not want to overlap with the Western Veil (Witches Broom) or Eastern Veil.  It helped that this was the same orientation that I used when I was imaging the Pelican.  I also wanted to get the luminous knots NGC 6979 and NGC 6974 located on the lower part of the image discovered by Lord Rosse (6974) and by William Herschel (6979). The designation NGC 6979 is often used to refer to Fleming’s Triangle.  I managed to get over 11 hrs of total exposure over 11 nights imaging after the Pelican went behind some trees.  Some more productive than others - one night invisible wispy clouds and another night the equipment gods abandoned me so nothing worked - fortunately they returned the next night. I enjoyed processing this image and I did have to get rid of a couple blown out star halos which I will post a video on in the near future.  On that same line, the nebula was done with Hydrogen and Oxygen filters but the stars were composed of RGB data.  I used a simple method of combining the star data in PixInsight - thanks Gary Imm!

Lastly, the first image is a typical HOO where Ha is in the red channel, OIII is in the green and blue channels.  Just for giggles I did a second image where Ha is in the red channel, Ha and OIII are split 50-50 in the green channel, and OIII is in the blue channel.  It gave a pretty neat looking color cast and I like the golden hue but I don't think it added any additional detail.

HOO

H(HO)O

Fleming's Triangle
Home Monroe, CT
Date: 9-16-19, 9-18-19, 9-21-19, 9-24-19, 9-25-19, 9-26-19, 9-27-19, 10-8-19, 10-14-19, 10-18-19
Camera: ZWO ASI1600MM-Pro
Telescope: Astro-Tech AT115EDT 115mm Refractor Telescope
Barlow: None
Focal Length: 805mm
f/7
Focal Reducer: Astro-Tech 0.8x Focal Reducer/Field Flattener for Refractor Telescopes
Mount: Orion Sirius EQ
Filter Wheel: ZWO EFW 8x 1.25"
Filter: ZWO Ha, OIII, R, G, B
Focuser: ZWO EAF
Autoguiding: QHY-5L-II-M attached to an Agena 50mm Guide Scope with Helical Focuser
Exposure: Ha 99 x 180s, OIII 100 x 180s, R 49 x 60s, G 29 x 60s, B 43 x 60s
Gain: 139
Offset 21
Temp: 13 C
Post Processing: PixInsight, Photoshop, APT
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