Hemisphere:  Northern  ·  Constellation: Cassiopeia (Cas)  ·  Contains:  IC1590  ·  NGC 281  ·  NGC281  ·  Sh2-184
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NGC-281 (Pacman Nebula), 


            Joel Shepherd
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NGC-281 (Pacman Nebula)

Imaging telescopes or lenses: Skywatcher Esprit 80ED APO Triplet

Imaging cameras: Atik 460EX Mono

Mounts: Advanced VX

Guiding telescopes or lenses: Orion Deluxe Mini 50mm Guide Scope with Helical Focuser

Guiding cameras: Orion StarShoot AutoGuider Pro Mono

Software: PixInsight 1.8  ·  Craig Stark Nebulosity 3

Filters: Astrodon 5nm H-alpha  ·  Astrodon 5nm Olll

Dates:Oct. 11, 2016

Astrodon 5nm H-alpha: 15x300" -10C bin 1x1
Astrodon 5nm Olll: 15x300" -10C bin 1x1

Integration: 2.5 hours

Avg. Moon age: 9.63 days

Avg. Moon phase: 73.02%

Bortle Dark-Sky Scale: 6.00

Astrometry.net job: 1304944

RA center: 0h 52' 32"

DEC center: +56° 45' 2"

Pixel scale: 2.431 arcsec/pixel

Orientation: -110.936 degrees

Field radius: 0.581 degrees

Resolution: 1280x1147

Locations: Home, Seattle, WA, United States


Subject: NGC-281 (Pacman Nebula), near Cassiopeia. Discovered in 1883 by E.E. Barnard, NGC-281 is at a distance of ~9500 light years, and is about 48 light years across. Its emissions are primary driven by the open star cluster IC-1590, while the darkest regions are primarily dust and are areas of active star formation. [Derived from Wikipedia entry]

Capture notes: I've started doing a few "One Night Wonders": capturing what I can in a single night and making the most of processing. In some cases it's simply because the commitment to a multi-night effort is too much. In this case, as it turned out, we didn't even get another night! There has been one clear evening in Seattle in the month of October. Other than a moon approaching full, I thought the skies were pretty clear. Early on in processing, it was evident that some thin clouds passed over while capturing the O-III lights.

Processing: This is HOO, with green augmented with a little HA, and the O-III boosted a bit in blue. The O-III required a pretty heavy hand on noise reduction. Luminance (full stack of all lights) had some weird speckling artifacts which PixInsight's cosmetic correction dealt with. Combined HA and O-III "tone maps", boosted saturation and darkened hues, applied luminance and that was about it.


Sky plot

Sky plot


NGC-281 (Pacman Nebula), 


            Joel Shepherd