Celestial hemisphere:  Northern  ·  Constellation: Pegasus (Peg)  ·  Contains:  NGC 7317  ·  NGC 7318  ·  NGC 7319  ·  NGC 7320  ·  NGC 7331  ·  NGC 7335  ·  NGC 7337  ·  NGC 7343  ·  Stephan's Quintet
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NGC 7331 and Environs, Deer Lick Galaxy Group and Stephan's Quintet, LRGB, 18-27 Oct 2017, 



    
        

            David Dearden
NGC 7331 and Environs, Deer Lick Galaxy Group and Stephan's Quintet, LRGB, 18-27 Oct 2017
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NGC 7331 and Environs, Deer Lick Galaxy Group and Stephan's Quintet, LRGB, 18-27 Oct 2017

Getting plate-solving status, please wait...
NGC 7331 and Environs, Deer Lick Galaxy Group and Stephan's Quintet, LRGB, 18-27 Oct 2017, 



    
        

            David Dearden
NGC 7331 and Environs, Deer Lick Galaxy Group and Stephan's Quintet, LRGB, 18-27 Oct 2017
Powered byPixInsight

NGC 7331 and Environs, Deer Lick Galaxy Group and Stephan's Quintet, LRGB, 18-27 Oct 2017

Acquisition details

Dates:
Oct. 18, 2017 ·  Oct. 27, 2017
Frames:
ZWO Blue 31 mm: 24×150(1h) (gain: 198.00) -20°C bin 1×1
ZWO Green 31 mm: 27×150(1h 7′ 30″) (gain: 198.00) -20°C bin 1×1
ZWO Luminance 31 mm: 105×150(4h 22′ 30″) (gain: 198.00) -20°C bin 1×1
ZWO Red 31 mm: 24×150(1h) (gain: 198.00) -20°C bin 1×1
Integration:
7h 30′
Avg. Moon age:
17.64 days
Avg. Moon phase:
23.85%

Basic astrometry details

Astrometry.net job: 1790955

RA center: 22h36m47s.8

DEC center: +34°1651

Pixel scale: 0.859 arcsec/pixel

Orientation: 90.455 degrees

Field radius: 0.684 degrees

Resolution: 4577x3450

File size: 9.2 MB

Locations: Mapleton Lateral Observatory, Mapleton, Utah, United States

Data source: Backyard

Description

I had a lot of problems acquiring this image. Intermittent clouds were an issue, as were the neighbor’s trees. The biggest problem was the flat calibration just didn’t work well. This produced color and brightness gradients I had to try to get rid of in post-processing. I guess I need to take some better flats. (And the overarching problem, a deadline I’m trying to meet for a National Science Foundation proposal on top of a bunch of other things at work!) Overall, it’s still the best image I have so far of this part of the sky. I can see I need to go a lot deeper if I want to do better. Also, maybe using a gain of 198 was not good here. Lower gain with longer exposures probably would have been better. I was really battling the sky glow, especially in the luminance. I’m not exactly in a dark sky site (Bortle orange, probably)!

Date: 18-27 Oct 2017

Subject: NGC 7331 and environs, Deer Lick Galaxy Group and Stephan’s Quintet

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 +PHD 2.6.4.4 (Win 10 ASCOM) using predictive PEC algorithm

Camera: ASI1600MM-Cool, -20 °C, Gain 198 Offset 50

Acquisition: Sequence Generator Pro 3.0.0.2

Exposure: 105x150 L 24x150 R, 27x150 G, 24x150 B,

Stacking: Neb 4.1.6, flats & darks, trans+rot align, Nebulosity 1.5σ stack and align.

Processing: StarTools 1.4.328: Aggressively stretched and deconvoluted L in StarTools. Combined RGB in Neb 4 and stretched, color balanced, deconvoluted (less aggressively) in StarTools. Used Carboni’s Astronomy Tools to remove horizontal and vertical pattern noise in the RGB, and smoothed it out, relying on the L for detail. Several rounds of “Less Crunchy More Fuzzy,” and several rounds of layer-masked curves + levels to get rid of nasty gradients. AstroFrame.

Comments

Sky plot

Sky plot

Histogram

NGC 7331 and Environs, Deer Lick Galaxy Group and Stephan's Quintet, LRGB, 18-27 Oct 2017, 



    
        

            David Dearden

In these public groups

ZWO ASI1600MM/QHY163M