NGC 2261 (also known as Hubble's Variable Nebula or Caldwell 46) is a variable nebula located in the constellation Monoceros. The nebula is illuminated by the star R Monocerotis (R Mon), which is not directly visible itself.
|Observation data: J2000.0 epoch|
|Right ascension||6h 39m 10s|
|Apparent magnitude (V)||9.0|
|Apparent dimensions (V)||2′|
|Designations||Hubble's Variable Nebula, Caldwell 46|
NGC 2261 was imaged as Palomar Observatory's Hale Telescope's first light by Edwin Hubble on January 26, 1949, some 20 years after the Palomar Observatory project began in 1928. Hubble had studied the nebula previously at Yerkes and Mt. Wilson. Hale had taken photographic plates with a 24-inch (60.96 cm) reflecting telescope in 1916. Also, plates were taken using the same telescope in 1908 by FC Jordan, this allowed Hale to use of a blink comparator to study any changes in the nebula.
The star R Monocerotis has lit up a nearby cloud of gas and dust, but the shape and brightness slowly changes visibly even in small telescopes over weeks and months, and the nebula looks like a small comet.
- "NGC 2261". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2007-04-11.
- "Hubble's Variable Nebula". www.nightskyinfo.com. Retrieved 2018-07-25.
- "Citizen Science".
- Hubble, E. P. (1916). "The variable nebula NGC 2261". Astrophysical Journal. 44: 190. Bibcode:1916ApJ....44..190H. doi:10.1086/142284.
- firstname.lastname@example.org. "Hubble's variable nebula (NGC 2261)". www.spacetelescope.org. Retrieved 2018-07-25.
- "Hubble's Variable Nebula, NGC 2261". Planetary Science Institute. 2010-10-15. Retrieved 2018-07-25.
- Arny, T. T.; Bechis, K. P. (1978). "A model for the cometary nebula NGC 2261". The Astrophysical Journal. 226: 455. Bibcode:1978ApJ...226..455A. doi:10.1086/156627.
- "NGC 2261: Hubble's Variable Nebula | Science Mission Directorate". science.nasa.gov. Retrieved 2018-07-25.
|Wikimedia Commons has media related to NGC 2261.|
- European Homepage for the HST – Hubble photos and information on NGC 2261
- wikispaces.com – Images by amateur astronomers
- NASA Astronomy Picture of the Day: NGC 2261: Hubble s Variable Nebula (November 8, 2017)
- NGC 2261 on WikiSky: DSS2, SDSS, GALEX, IRAS, Hydrogen α, X-Ray, Astrophoto, Sky Map, Articles and images