When is the best time to observe 23 Ursae Majoris?

23 Ursae Majoris is best observed from January through March, with peak visibility during February when it transits around midnight in the Northern Hemisphere.

Where is 23 Ursae Majoris located in the sky?

23 Ursae Majoris lies in the constellation Ursa Major at right ascension 09h 32m and declination +63° 04′.

What telescope do I need to split 23 Ursae Majoris?

Splitting 23 Ursae Majoris requires an aperture of roughly 60 mm or larger — the components are separated by about 22.7″ at magnitudes near 3.7. The companion is about 5.5 magnitudes fainter, so glare from the primary — not separation — sets the minimum aperture. Larger apertures and steady seeing help resolve the pair cleanly.

23 Ursae Majoris — Double Star in Ursa Major

Magnitude 3.7^m DoubleStar Ursa Major (UMa) Visible

Star Map + List + Plan

Observe

1Physical Properties

Magnitude 3.67

Variable Type Delta Scuti (Pulsating)

Spectral Type F0V

Star Color Yellow-white (B-V 0.33)

Distance 80 ly

2Position & Identifiers

RA 09h 31m 31.7s

Dec +63° 03' 43.0"

Constellation Ursa Major (UMa)

HR 3757

HIP 46733

HD 81937

SAO 14908

Flamsteed 23 UMa

Double Cat 7402

SIMBAD

3How easy to split?

Primary 3.7 mag Companion 9.2 mag Separation 22.7″

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

Easy Medium Hard Very hard Impossible

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

4Visibility

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Best season Jan – Mar (peak: Feb)

5Multiple Star System Triple C: optical

Components 3 (triple)

Component IDs AB

Separation 22.7″

Companion Mag 9.2

Companion Sp K5V

Position Angle 267°

Star Colors A: Yellow-white B: Red

Discoverer STF1351

Notes

AB binary. C, 10.5v at 100", optical.

Separation over time

Measured 1781 → 2016 (235 y)

Separation drift 19.2" → 22.7" (+3.50")

Rate +0.0149" / y

PA drift 273° → 267° (-6°, -0.026°/y)

Slow change over generations — observable in lifetime comparisons.

Measured from the WDS observational archive. No orbital solution has been derived — most likely the period is too long to fit an orbit to the available measurement arc.