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October Deep Sky Challenge: NGC 281, "The Pacman Nebula"
October Deep Sky Challenge: NGC 281,

You've been challenged by visual astronomer Roger Ivester to find the Emission Nebula NGC 281 in Cassiopeia, also known as "The Pacman Nebula," for obvious reasons. Leave a comment on this article if you find it.

Located about 2.5 east of the bright star Alpha Cassiopeia, is emission nebula, NGC 281. This is a very large and faint nebula, with low surface brightness. It was discovered in 1883, by E.E. Barnard. This nebula is often called the "Pacman Nebula" due to its similarity to the video game character, however, an O-III filter is required to see this unique shape and feature. The nebula is in excellent position for both early to late fall observing.

What is an emission nebula? An emission nebula is an ionized-hydrogen region whose spectrum consists of emission lines by a glowing gas under low pressure.

The following image was made by Dr. James Dire, formerly of North Carolina, now residing in Hawaii. Dire used an Orion 190 mm Maksutov-Newtonian f/5.3 to make this beautiful image.


Credit: Dr. James Dire
 

I found NGC 281 to be very challenging when using a 10-inch reflector from my moderately light polluted backyard in the foothills of western North Carolina. It was visible with my 8 x 50 finder, but very dim. At 57x, this object appears mostly round with very little detail. When increasing the magnification to 104x, and adding an O-III filter, this nebula really came to life. The northern part is rounded, resembling a helmet. Just below the rounded northern part is an area devoid of any nebulosity, and to the east is a section which curves toward the southeast. The nebulosity is much more concentrated and quite a bit brighter in the northeast. The southeastern curving tail is difficult, even with the use of the O-III filter, mostly due in-part to several unshielded streetlights being nearby.

In the central region is a faint triangle of four stars, however, I could only see three. This multiple star is Burnham 1, named after S.W. Burnham. This small group of bluish-white stars really adds to the beauty of this object. The misty nebula, encapsulating the trio of stars creates a beautiful sight, but there's even more. IC 1590, a small and very faint open star cluster is also located within the nebula, but I was unable to see or recognize this cluster. Can you?

The following sketch was made using a No. 2 pencil, and a blank 5 x 8 note card. The colors were inverted using my scanner. The telescope used was a 10-inch f/4.5 reflector with the employ of an O-III narrowband nebula filter.

 

Sue French from New York, using a 10-inch reflector said: "Nice large nebula, improved with a UHC filter, even better with an O-III. When using a 4.1-inch refractor, a faint nebula surrounding a pretty trio of stars." Jaakko Saloranta of Finland said: "bright enough to be spotted under less than good skies, using a 4.8-inch refractor with an O-lll filter."

Gus Johnson of Maryland: "found it easily with a 4 1/4-inch reflector. In the fall of 1968, using a 6-inch reflector at 148x, was able to see all four stars of Burnham 1." Note: (Gus Johnson was the founder of SN 1979C, and only the third amateur at that time to have visually discovered a supernova.)

Fred Rayworth of Nevada, using a 16-inch reflector from Cathedral Gorge: "a mostly round nebula at 102x, but when adding an O-III the "Pacman" shape was easy. Could see only three stars in Burnham 1."

What about you? Are you up for the challenge? Leave a comment in the review section of this article, and let us know what you made of the Pacman Nebula, and of course, where you're viewing from and what aperture and filters you're working with. Good luck!

Roger Ivester has enjoyed the wonders of the night sky since he was 12 years old. He is a visual observer and enjoys sketching and writing about what he sees. In 2009 he helped start the Las Vegas Astronomical Society Observers Challenge, and works with Fred Rayworth on a monthly basis to compile the report. Roger and his wife Debbie live in the foothills of western North Carolina.

Details
Date Taken: 10/03/2013
Author: Roger Ivester

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