Beta Monocerotis (β Mon)

Beta Monocerotis (β Mon) is a double star in the constellation Monoceros, magnitude 4.6.

A superb triple of blue-white stars, described by William Herschel as one of the most beautiful sights in the heavens. Its components (magnitudes 4.6 and 5.0; spectral types B4 V (blue-white) and B2 V (blue-white)) lie 7.3″ apart at PA 132° (measured 2022). B and C (magnitudes 5.0 and 5.3) are themselves 2.6″ apart.

When and where to see it

It is best placed in the evening sky around January, when it crosses the meridian at about 10 pm local time (around midnight in December). It can be seen from everywhere south of 83°N and never sets south of 83°S.

At its highest it stands 33° up from 50°N, 48° up from 35°N, 83° up from the equator, 62° up from 35°S.

Facts

Type

Double star

Constellation

Monoceros

Designations

β Mon, 11 Mon, 11 Monocerotis, STF 919, HIP 30867

Magnitude

4.6

Position

RA 6h 28.8m, Dec −7° 2′ (J2000)

Open AstroPilot to see when Beta Monocerotis (β Mon) is highest tonight from your location, how easy it is with your telescope or binoculars, and an eyepiece view.