This object is also known by the names of the Hubble Variable Nebula or Caldwell 46. This variable nebula that is in the constellation of Monoceros, is illuminated by a star that we can not see called R Monocerotis (R Mon). This star is massive, it is located at the southern extremity of the nebula, it is a very young Tauri with about 300,000 years, it can be about ten times the mass of our star the Sun. It is about 2500 years away.
NGC 2261 was photographed for the first time through the Hale telescope at the Palomar Observatory by Edwin Hubble on January 26, 1949. A proposed example for variability is that dust clouds near R Mon periodically block the star's illumination.