NGC 2261, Hubble's variable nebula

Hubble's variable nebula is in Monoceros and was the first object to be photographed with the famous 200 inch Palomar telescope in 1948. This curious object is a reflection nebula in which is embedded the star R Monocerotis. Variations in the appearance of the nebula were noted by the American astronomer Edwin Hubble in 1916. They are probably caused by opaque clouds of dust passing between the hidden star and the outskirts of the nebula we see, the moving shadows changing the apparent form of the glowing dust in an irregular way. This picture was made from three AAT plates taken over several years and subtle colour changes around the edge of the nebula are indications of the variability.

Entry from NGC 2000.0 (R.W. Sinnott, Ed.) © Sky Publishing Corporation, 1988:

NGC 2261  Nb 06 39.2  +08 44 s  Mon   2.         B, vmE 330deg , N com = *11

Related image
UKS 29 The Cone nebula, Trumpler 5 and NGC 2261