Celestial hemisphere:  Northern  ·  Constellation: Draco (Dra)  ·  Contains:  NGC 4236
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NGC 4236, Spiral Galaxy in Draco, OSC (UHC-S), 2-3 Apr 2016, David Dearden
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NGC4236, Spiral Galaxy in Draco, OSC (UHC-S), 2-3 Apr 2016

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Description

This was a first-time observation of NGC4236, which is quite dim but of good size for my optics. This galaxy is not so frequently imaged, perhaps because it is so dim and because it is hard to make out a lot of internal structure. This was also my first opportunity to try my fix for the Sequence Generator Pro plate solving problems I've had for the last month. (The problems don't really belong to SGP; they belong to me!) It turns out all I needed to do was correctly set the aspect ratio parameter for PlateSolve2 to account for the non-square pixels in my DSI IIc imaging camera. I did numerous successful plate solves during this session. Actually I did too many, because the other problem that has plagued me recently, image download failure, was quite evident during this session. It happened with the guider quite a few times as I set up and the session did eventually fail due to a main image download failure. I suspect the fix for that will be a more capable powered USB hub than the cheap ones I've been using. Anyway, plate solving now works great and I also did a successful unattended meridian flip.

Date: 2-3 Apr 2016

Subject: NGC4236, spiral galaxy in Draco

Scope: AT8IN

Filter: Baader Planetarium UHC-S

Mount: EQ-6 (EQMOD)

Guiding: Orion ST-80 + Antares 0.5x focal reducer + DSI Ic + PHD 2.6.1.1 (Win 7 ASCOM)

Camera: DSI IIc, no chiller CCD 10 °C

Acquisition: Sequence Generator Pro 2.5.0.23 with Nebulosity 4.0.4 ASCOM camera driver

Exposure: 33x600 s

Stacking: Neb 4, bad pixel map, bias included, 33 flats, match histograms, trans+rot align, Deep Sky Stacker 1.5σ κ-σ stack without drizzle.

Processing: StarTools 1.4.305: Crop; Wipe; Develop: 85.00%; HDRptimize; Color:Scientific, 277% saturation, red bias reduce at 1.19; Deconvolute: 2.8 pix; Life:Moderate; Track: Smoothness 87%, 6.0 pix; Magic, shrink 2 pix. Photoshop CS6 + Astronomy Tools: Deep space noise reduction; Increase star color; curves; layer-masked levels to kill gradient; Astroframe.

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NGC 4236, Spiral Galaxy in Draco, OSC (UHC-S), 2-3 Apr 2016, David Dearden