NGC 2261

Variable fog ( reflection fog )
NGC 2261

Photo from the Hubble Space Telescope
Constellation	unicorn
Position equinox : J2000.0
Right ascension	06h 39m 09.5s
declination	+ 08 ° 44 ′ 40 ″
Further data
Brightness (visual)	9.0 likes
Angular expansion	3 ′, 0 × 2 ′, 0
distance	2600 ly
history
discovery	William Herschel
Date of discovery	December 26, 1783
Catalog names
NGC 2261 • Caldwell 46, H IV 2, h 399, GC 1437
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NGC 2261 (also Hubble's Variable Nebula and Caldwell 46 ) is a variable reflection nebula in the constellation Monoceros , which is about 2,600 light-years from the sun away. It is illuminated by a young giant star of the spectral type B0 called R Monocerotis (R Mon), but which is not itself visible.

NGC 2261 was photographed as the " first light " of the Hale telescope by Edwin Hubble on January 26, 1949. Hubble had already studied the nebula at the Yerkes and Mount Wilson observatories .

One thesis for the variability are dense dust clouds in the vicinity of R Mon, which periodically block its illumination.

The object was discovered by Wilhelm Herschel on December 26, 1783 .

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