When is the best time to observe Dubhe?

Dubhe is best observed from February through April, with peak visibility during March when it transits around midnight in the Northern Hemisphere.

Where is Dubhe located in the sky?

Dubhe lies in the constellation Ursa Major at right ascension 11h 04m and declination +61° 45′.

What telescope do I need to split Dubhe?

Splitting Dubhe requires an aperture of roughly 430 mm or larger — the components are separated by about 0.8″ at magnitudes near 1.8. The companion is about 3.2 magnitudes fainter, so glare from the primary — not separation — sets the minimum aperture. Larger apertures and steady seeing help resolve the pair cleanly.

Dubhe — Double Star in Ursa Major

HIP 54061; Alpha Ursae Majoris; 50 Ursae Majoris

Magnitude 1.8^m DoubleStar Ursa Major (UMa) Visible

Star Map + List + Plan

About Dubhe

Description

Dubhe is an orange giant of spectral type K0IIIa at magnitude 1.79, the second brightest star in Ursa Major. Located about 124 light-years from Earth, it has a luminosity of roughly 316 times solar. Dubhe is a spectroscopic binary with a fainter yellow-white companion. Unlike most Big Dipper stars, Dubhe is NOT a member of the Ursa Major Moving Group.

Observing Tips

Dubhe is the upper-right star of the Big Dipper's bowl (when upright). Together with Merak, it forms the famous Pointer Stars — a line through them extended northward about 5 times their separation leads to Polaris. Its warm orange color is subtle but noticeable compared to the whiter Dipper stars. Visible year-round from mid-northern latitudes.

History

The name Dubhe comes from the Arabic 'dubb,' meaning 'bear,' referring to the Great Bear. As a Pointer Star, Dubhe has been essential for navigation and orientation for millennia. Like Alkaid at the Dipper's tail, Dubhe's independent motion (not part of the Moving Group) means the Dipper's shape is slowly changing.

Fun Facts

Because Dubhe and Alkaid are not members of the Ursa Major Moving Group (while the five inner stars are), they are moving in different directions. In about 50,000 years, the Big Dipper will no longer look like a dipper — its shape will gradually deform as these outlier stars drift away.

Observe

1Physical Properties

Magnitude 1.79

Spectral Type G8III giant

Star Color Orange (B-V 1.07)

Distance 123 ly

2Position & Identifiers

RA 11h 03m 43.7s

Dec +61° 45' 03.0"

Constellation Ursa Major (UMa)

HR 4301

HIP 54061

HD 95689

SAO 15384

Bayer Alpha

Flamsteed 50 UMa

Double Cat 8035

SIMBAD Wikipedia

3How easy to split?

Primary 1.8 mag Companion 5.0 mag Separation 0.8″

Telescope	Bortle 3	Bortle 4	Bortle 5
80 mm refractor 80mm refr.	V. hard	V. hard	V. hard
150 mm Newton 150mm Newt.	V. hard+	V. hard+	V. hard+
Celestron C8 (203 mm SCT) C8 203mm	V. hard+	V. hard+	V. hard+

Easy Medium Hard Very hard Impossible

Bortle 3 = rural · 4 = outer suburbs · 5 = suburbs

To reach "Medium" at Bortle 3, you'd need at least a 430 mm reflector.

4Visibility

Set a location in User Settings to see visibility data.

Best season Feb – Apr (peak: Mar)

5Multiple Star System

Separation 0.8″

Companion Mag 5.0

Position Angle 342°

Star Colors A: Orange

Discoverer BU 1077

Notes

1.87 K0III, 4.81 F0V, 44.4y, a = 0.603". Also classified K0II-III + A8V:. Combined mag., colors. Also CPM at 280" | with HD 95638 = GC 15179, 7.12V F8; SB, 6.04d.