Hemisphere:  Northern  ·  Contains:  IC 1590  ·  NGC 281
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NGC 281 • Pacman Nebula in SHO, 


            Douglas J Struble
NGC 281 • Pacman Nebula in SHO
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NGC 281 • Pacman Nebula in SHO

Technical card

Imaging telescopes or lenses: Stellarvue SVX102T-R  ·  Explore Scientific 152 mm Carbon Fiber

Imaging cameras: ZWO ASI1600MM-Cool

Mounts: Astro-Physics Mach 1 GTO  ·  Orion Atlas Pro AZ/EQ-G

Guiding telescopes or lenses: Orion 80mm Short Tube  ·  ZWO 60mm Guidescope

Guiding cameras: ASI224MC  ·  Starlight Xpress Lodestar x2

Software: Photoshop CC  ·  PHD2  ·  Sequence Generator Pro  ·  PixInsight

Filters: Astronomik SII 1.25" 6nm  ·  Astronomik Deep-Sky G  ·  Astronomik Deep-Sky R  ·  Astronomik Deep-Sky B  ·  Astronomik Ha 6nm 1.25''  ·  Astrodon Ha 5nm  ·  Astrodon SII 3nm  ·  Astrodon OIII 3nm

Accessory: QHYCCD PoleMaster  ·  ZWO 8x 1.25" Filter Wheel (EFW)  ·  Hotech 2" SCA Self-Centering Field Flattener  ·  MoonLite CFL 2.5" Large Format Focuser

Dates:Aug. 5, 2017Aug. 6, 2017Aug. 7, 2017Aug. 12, 2020Sept. 25, 2020Oct. 4, 2020

Astrodon Ha 5nm: 99x120" (gain: 139.00) -20C bin 1x1
Astrodon OIII 3nm: 97x120" (gain: 139.00) -20C bin 1x1
Astrodon OIII 3nm: 239x120" (gain: 200.00) -20C bin 1x1
Astrodon SII 3nm: 110x120" (gain: 139.00) -20C bin 1x1
Astrodon SII 3nm: 308x120" (gain: 200.00) -20C bin 1x1
Astronomik Ha 6nm 1.25'': 386x120" (gain: 200.00) -20C bin 1x1

Integration: 41.3 hours

Darks: ~50

Flats: ~50

Bias: ~250

Avg. Moon age: 14.92 days

Avg. Moon phase: 82.43%

Bortle Dark-Sky Scale: 8.00

Basic astrometry details

Astrometry.net job: 3933487

RA center: 0h 52' 48"

DEC center: +56° 40' 33"

Pixel scale: 1.105 arcsec/pixel

Orientation: 119.267 degrees

Field radius: 0.470 degrees

Resolution: 2510x1750

Data source: Backyard


I have been trying to go after more obscure objects these days, but there is not a lot rising now that are large enough for my secondary rig's shorter focal length. So I decided to go back and return to one of my first narrowband projects from three years ago; the Pacman Nebula (NGC 281 | Sh2-184). I had two major goals; one to resolve more detail and second, to pick up more fainter nebulosity off to the left of the image. Here was my first attempt three years ago:


NGC 281, IC 11 or Sh2-184 is a bright emission nebula and part of an H II region in the northern constellation of Cassiopeia and is part of the Milky Way's Perseus Spiral Arm. This 20×30 arcmin sized nebulosity is also associated with open cluster IC 1590, several Bok globules and the multiple star, B 1. It collectively forms Sh2-184, spanning over a larger area of 40 arcmin. Colloquially, NGC 281 is also known as the Pacman Nebula for its resemblance to the video game character.

Edward Emerson Barnard discovered the nebula in August 1883, describing it as "a large faint nebula, very diffuse." Multiple star 'B 1' or β 1 was later discovered by S. W. Burnham, whose bright component is identified as the highly luminous O6 spectral class star, HD 5005 or HIP 4121. It consists of an 8th-magnitude primary with four companions at distances between 1.4 and 15.7 arcsec. There has been no appreciable change in this quintuple system since the first measures were made in 1875.



Douglas J Struble

Sky plot

Sky plot


NGC 281 • Pacman Nebula in SHO, 


            Douglas J Struble

In these public groups

Sharpless2 Objects