My immediate prior image included lots of “firsts;” this one may include lots of “lasts” thanks to the **!#!! sprinkler system. Despite verifying the switch on the sprinkler controller was in the “off” position, the cussed switch stuck and the cussed thing went off last night; my gear got a couple of hours’ worth of watering. I can fix the scope and the PicGoto controller, but if the cameras or the motors on the mount are damaged, I’m done. Anyway, prior to that disaster, conditions for this image were not great: high clouds, which ultimately ended the session about 3 hours in. Contrast was therefore less than optimal. I have only imaged this object once before, 3 years ago, so the new result, even with all the issues, was a lot better. Interestingly, Nebulosity stacking resulted in a blue/purple color for the nebula, whereas Deep Sky Stacker drizzle stacking (which is what I present here) resulted in a more greenish cast. I’m not sure which is more accurate. And it kind of does look like a skull. Maybe that will turn out to be appropriate!

Date: 7 Oct 2015

Subject: NGC 246, Skull Nebula

Scope: AT8IN

Filter: Baader Fringe Killer

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

Guiding: 9x50 Finder/Guider + 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: 19x600 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 77.97%; HDR optimize; Color: scientific, 250%; Deconvolute 3.2 pix; Life: moderate; Track 8.0 pix, Smoothness 88%; Repair: Redistribute, core avg.; Magic: shrink 3 pixels. CS6 Astronomy Tools deep space noise reduction; space noise reduction; make stars smaller; levels; debloat stars with liquify/pucker filter; Astroframe.