NGC 3718 & 3729, LRGB, 10 Apr 2018 (David Dearden)

NGC 3718 & 3729, LRGB, 10 Apr 2018

I’ve always thought NGC 3718 looked cool, and inasmuch as it is galaxy season and my best previous image of this area is pretty bad, I decided to give it a try. Had high thin clouds during at least some of the session. The initial RGB stack was quite green, so I had to back that off a bit. In another “first” for me, I used my i5 Windows acquisition computer with the new DeepSkyStacker 64-bit application to do all the stacking prior to moving to my MacBook for post-processing. I need to get online and see what I can learn about LRGB processing. So far I’ve pretty much been guessing so some more formal training is in order. However, this is definitely better than my 2014 image so I’m happy with it.

Date: 9-10 Apr 2018

Subject: NGC 3718, NGC 3729

Scope: AT8IN+High Point Scientific Coma Corrector

Filters: ZWO 31 mm diameter unmounted L, R, G, B

Mount: EQ-6 (EQMOD 2.000j)+PEC

Guiding: Orion Thin Off-axis Guider + DSI Ic +PHD 2.6.4.dev9 (Win 10 ASCOM)

Camera: ASI1600MM-Cool, -20 °C, Gain 139 Offset 21

Acquisition: Sequence Generator Pro 3.0.1.0

Exposure: 36x300 L, 20x180 R, 20x180 G, 20x180 B

Stacking: Deep Sky Stacker 4.1.0 (64-bit) dark+flat+bias, κ-σ stacking with κ = 1.5.

Processing: StarTools 1.4.332: Did RGB combination using Annie’s Astro Actions. Binned 2x2 in StarTools. Used StarTools’ “Wipe”, then aggressively stretched and deconvoluted L and RGB separately in StarTools. Increased green bias reduction and used “cap green to brown” in StarTools’ color module. Aligned the processed layers in DSS then combined in Photoshop. Used Astronomy Tools’ increase star color, some additional deep space & space noise reduction, followed by “less crunchy more fuzzy”, AstroFrame.

Original
Final
B

B

Description: In this version I experimented with creating a feathered layer mask using Astronomy Tools’ “Select Brighter Stars”, then used “Make Stars Smaller” (repeatedly) and “Increase Star Color” (repeatedly) to tighten up the brighter stars and bring out a little more color without losing or messing up the dimmer stars. I’m not sure I can tell much difference, but here it is.

Uploaded: ...

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ZWO ASI1600MM/QHY163M

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Status	Advanced success
Started	...
Astrometry.net job	2006497
PixInsight job	1SF48IND1889UI350ABF6P3MCM42UW46
PixInsight queue size	n/a
PixInsight stage	n/a

RA (center)	11h32m44s.74
RA (top/left)	11h28m55s.63
RA (top/right)	11h36m04s.30
RA (bottom/right)	11h36m37s.54
RA (bottom/left)	11h29m21s.80

Dec (center)	+53°06′07″.7
Dec (top/left)	+52°44′25″.6
Dec (top/right)	+52°38′36″.3
Dec (bottom/right)	+53°27′23″.6
Dec (bottom/left)	+53°33′16″.9

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