The sky around Rosette Nebula at true scale, north up and east left, with stars to magnitude 8. The circles show the field of a low-power eyepiece and of 10×50 binoculars.
Rosette Nebula is a diffuse nebula in Monoceros, 4,620 light-years away
Rosette Nebula (Caldwell 49, NGC 2237, NGC 2238, NGC 2239, NGC 2246, LBN 948) is a diffuse nebula in the constellation Monoceros, 4,620 light-years away. It shines at magnitude 9.0 and spans 1.3° × 1° of sky, about 108 light-years across. It is visible in 10×50 or larger binoculars, and it is highest in the evening sky in February.
Nebula: a cloud of gas and dust. Emission nebulae glow on their own, lit by ultraviolet light from hot young stars; reflection nebulae shine by starlight scattered from dust; dark nebulae block the light behind them.
Rosette Nebula is Sh2-275 in the Sharpless catalog
Stewart Sharpless listed it in his catalog of H II regions (1959), drawn from the red and blue prints of the Palomar Sky Survey. He rated each region's brightness on a scale of 1 to 3; Sh2-275 is bright (class 3 of 3). It is also listed as LBN 949, LBN 948.
Finding Rosette Nebula from Betelgeuse
Rosette Nebula lies 9.2° east of Betelgeuse, the magnitude 0.5 star. A fist held at arm's length covers about 10°.
Rosette Nebula is highest in the evening in February
The chart gives its height above the horizon at 9 pm through the year, from 60°N to 40°S. It can be seen from the whole northern hemisphere and south to about 85°S.
Rosette Nebula is 4,620 light-years away
The light seen from Rosette Nebula tonight left it about 4,620 years ago. It ranks 31 of 109 by distance among the 109 Caldwell objects. Distance source: Gaia DR3, Hunt and Reffert 2023.
