Celestial hemisphere:  Northern  ·  Constellation: Cepheus (Cep)  ·  Contains:  NGC 7538
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NGC 7538, OSC, 13 Oct 2015, David Dearden
NGC 7538, OSC, 13 Oct 2015
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NGC 7538, OSC, 13 Oct 2015

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Description

Worked on collimating the AT8IN with my Antares laser collimator prior to taking this image, and everything looks a lot better than before (rotating the collimator in the eyepiece holder was shifting the laser spot around before; not now). Had no problem finding this nebula, which was a first-time observation for me. It was an easy PicGoto from β Cas. Also had no trouble getting a nice, tight fine focus with Nebulosity, so maybe my problems the night before were due to poor collimation. Guiding started off really well, but something went way wrong about an hour after the meridian flip. Almost always these are balance issues with my mount, although I can't rule out having a cable hang up somewhere. The plan for this image is to add H-α later on a night when there's a bit more Moon, but the OSC RGB turned out well enough it will be interesting to see whether H-α adds much. The color shading in the nebula is very sensitive to which monitor I use to look at it; it looks pretty good on my Retina display, but not so good on my Dell flat panel.

Date: 13 Oct 2015

Subject: NGC 7538, emission nebula near the Cassiopeia/Cepheus border

Scope: AT8IN

Filter: Baader Fringe Killer

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

Guiding: Orion ST-80 + DSI Ic + PHD 2.5.0.1 (Win 7 ASCOM)

Camera: DSI IIc, no chiller CCD 15 °C

Acquisition: Nebulosity 4.0.3, no dither

Exposure: 16x600 s

Stacking: Neb 4, bad pixel map, bias included, 33 flats, match histograms, deBayer & square, trans+rot align, DSS 2x drizzle 1.75 average κ-σ stack.

Processing: StarTools 1.4.305 Crop; Wipe 75%; Develop 79.2%; HDR optimize; Color: scientific, 200%; Deconvolute 5.5 pix; Life:moderate; Track 10.0 pix, Smoothness 90%; Magic: shrink 3 pixels. CS6 Astronomy Tools deep space noise reduction; increase star color; make stars smaller; liquify/pucker; levels & curves; Astroframe.

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NGC 7538, OSC, 13 Oct 2015, David Dearden