NGC 281

NGC 281
NGC 281 in the optical (red, yellow) and X rays (blue)
Observation data: J2000.0 epoch
Type	Emission
Right ascension	00h 52m 59.3s[1]
Declination	+56° 37′ 19″[1]
Distance	9.5 kly (2.9 kpc)[2]
Apparent dimensions (V)	35′
Constellation	Cassiopeia
Physical characteristics
Radius	unknown
Absolute magnitude (V)	Unknown
Other designations	IC 11,[1] Sharpless 184, Pacman Nebula
See also: Diffuse nebula, Lists of nebulae
v · d · e

NGC 281 is an H II region in the constellation of Cassiopeia and part of the Perseus Spiral Arm. It includes the open cluster IC 1590, the multiple star HD 5005, and several Bok globules. Colloquially, NGC 281 is also known as the Pacman Nebula for its resemblance to the video game character.

The nebula was discovered in August 1883 by E. E. Barnard, who described it as "a large faint nebula, very diffuse." The multiple star HD 5005, also called β1, was discovered by S. W. Burnham. It consists of an 8th-magnitude primary with four companions at distances between 1.4 and 15.7 seconds of arc. There has been no appreciable change in this quintuple system since the first measurements were made in 1875.

The nebula is visible in amateur telescopes from dark sky locations. In his book Deep Sky Wonders, Walter Scott Houston describes the appearance of the nebula in small telescopes:^[3]

There was a faint glow in the immediate vicinity of the multiple star, with an occasional impression of a much larger nebulosity...Its surface brightness was much less than that of M33 in Triangulum or NGC 205, the distant companion of the Andromeda galaxy.

Gallery

• 

  Young open star cluster IC 1590, which is found within the star formation region NGC 281

• 

  NGC 281 - Amateur Narrowband Image ([SII] = Red, H-alpha = Green, [OIII] = Blue)

• 

  Composite image of NGC 281

References

1. ^ ^{a b c} "NASA/IPAC Extragalactic Database". Results for NGC 281. http://nedwww.ipac.caltech.edu/. Retrieved 2006-10-17. 
2. ^ Leass, E. A.; Biller, B.; Dame, T. M.; Megeath, S. T. (2001). "An Expanding Complex of Molecular Clouds High Above the Perseus Spiral Arm". American Astronomical Society, 199th AAS Meeting, #91.16; Bulletin of the American Astronomical Society 33: 1439. Bibcode 2001AAS...199.9116L. 
3. ^ Houston, Walter Scott (2005). Deep-Sky Wonders. Sky Publishing Corporation. ISBN 1931559236. 

External links

• NGC 281 Astronomy picture of the Day (August 23, 2005) at NASA
• NGC 281 at ESA/Hubble

Coordinates: 00^h 52^m 53.8^s, +56° 37′ 29″