The sky around vdB 81 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.
vdB 81 is a reflection nebula in Monoceros, 2,680 light-years away
vdB 81 (IC 448, LBN 931, Ced 79) is a reflection nebula in the constellation Monoceros, 2,680 light-years away. spans 15′ of sky, about 12 light-years across. It is a telescope object, 6 inches or larger, 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.
vdB 81 is vdB 81 in the Van den Bergh catalog of reflection nebulae
Sidney van den Bergh listed it in his catalog of reflection nebulae (1966), drawn from the Palomar Sky Survey. He chose nebulae lit by a star bright enough to appear in the Bonner and Cordoba star catalogs. The star that lights it is 13 Mon, HD 46300, A0Ib, magnitude 4.5. He rated it moderate in brightness and very blue in color.
Finding vdB 81 from Betelgeuse
vdB 81 lies 9.4° east of Betelgeuse, the magnitude 0.5 star. A fist held at arm's length covers about 10°.
vdB 81 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 83°S.
vdB 81 is 2,680 light-years away
The light seen from vdB 81 tonight left it about 2,680 years ago. It ranks 103 of 158 by distance among the Van den Bergh nebulae. Distance source: Gaia DR3 parallax of the illuminating star via AT-HYG v3.2 (822 pc).
