The Night of the Trifid (Nebula)

I’ve gotten home from a quick camping trip and have emerged from a period of too much moonlight, so I’m back to imaging again. The desire to get that H-⍺ filter is building, but I have not yet succumbed. 

It would have been nice to use last night on the Trifid Nebula, which is very interesting because it combines H-⍺ emission regions, which are red, with reflection regions, which appear blue. I synched on Antares, farther from the target than usual, but the goto was right on. Conditions were not great. Though the sky started out quite clear, there was also a lot of smoke in the air from the ubiquitous wildfires we seem to have every summer. The night was warm; the camera started at 26 °C but the chiller at 2.5 A pulled it down to 15 °C. The other problem was intermittent light wind gusts, which made the guiding problematic. The subframes definitely got worse when the Moon rose, but M20 is quite low on my horizon so I kept all the subs I could.  All things considered, I'm happy with the image because it is a big improvement over last year’s, and the best Trifid I’ve gotten so far.

Date: 17 Jul 2014

Subject: M20, Trifid Nebula

Scope: AT8IN

Filter: Baader UHC-S

Mount: CG-5 (Synta motors, PicGoto Simplificado)

Guiding: 9x50 Finder/Guider + DSI Ic + PHD 2.3.0 (Win 7 ASCOM)

Camera: DSI IIc chiller at 2.50 A, 15 °C

Acquisition: Nebulosity 3.2.0, no dither

Exposure: 37x180 s

Stacking: Neb 3, bad pixel map, bias included, normalize first, trans+rot align, 1.5 SD stack.

Processing: StarTools 1.3.5.279 Crop; Wipe:Color & brightness 75%; Develop 82.80%; HDR:Reveal DSO core; Color:Scientific, 200%; Deconvolute auto mask 2.6 pix; Life:Moderate; Track RNC 2.00%; Magic:Shrink 1 pix;  CS6 Astronomy Tools Healing brush; Increase star color; Less crunchy more fuzzy; Astro Frame.

For comparison, here’s last year’s effort, which involved 600-second subframes. I guess if I get that H-⍺ filter I’ll be doing those more frequently. I also used the coma corrector so the field of view is a bit smaller, and the image is flipped 180°.

Date: 2 Jul 2013

Subject: M20, Trifid Nebula

Scope: AT8IN + HPS Coma Corrector

Filter: Baader UHC-S

Mount: CG-5 (Synta motors)

Guiding: 9x50 Finder/Guider + DSI Ic + PHD 1.14.2

Camera: DSI IIc (chiller at ~2.5 A, T = 19-20 °C)

Acquisition: Nebulosity 3.1.6, no dither

Exposure: 21x600 s

Stacking: Neb 3, bad pixel map, bias included, normalize first, trans+rot align, 1.5 SD stack.

Processing: StarTools 1.3 Crop; Wipe:Color & Brightness; Develop 95.97%; Contrast; HDR:Optimize; Sharpen; Deconvolute: 2.4 pix; Track; Color:Bottom 2.0, Top Full, Sat 400%; Magic:Shrink 2; Magic:Tighten 1; Life:Moderate.  Processed another layer identically, except I used HDR:Reveal with noise reduction enabled.  CS6+Astronomy Tools Increase star color; deep space noise reduction; space noise reduction; Gaussian blurred (4 pix) high pass filter; blended in the core reveal layer at 50% transparency; less crunchy more fuzzy; AstroFrame.