NGC 2261

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Description:    This fascinating nebula was discovered by Friedrich Herschel in 1783. It is known as "Hubble's Variable Nebula", though, because Hubble noticed that it changed appearance over time. R Monocerotis is the bright star behind the narrow end of the nebula. It is believed that R Mon is ejecting material drawn from an accretion disk, thus forming the paraboloid shape that we see here (similar to a stemless wineglass on its side). It is thought that material in the accretion disk orbiting RMon casts shadows on the nebula, thus accounting for its changing appearance.
Constellation: Monoceros
Distance: 2,500 light years
Apparent Size: 2' x 1'
Date: 27, 28 january 2006
Equipment: 12" RCOS RC, ST10XME, AP1200
Exposure: RGB: 150-135-95 minutes