When is the best time to observe Upsilon Ursae Majoris?

Upsilon 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 Upsilon Ursae Majoris located in the sky?

Upsilon Ursae Majoris lies in the constellation Ursa Major at right ascension 09h 51m and declination +59° 02′.

What telescope do I need to split Upsilon Ursae Majoris?

Splitting Upsilon Ursae Majoris requires an aperture of roughly 60 mm or larger — the components are separated by about 11.9″ at magnitudes near 3.8. The companion is about 7.5 magnitudes fainter, so glare from the primary — not separation — sets the minimum aperture. Larger apertures and steady seeing help resolve the pair cleanly.

Upsilon Ursae Majoris — Double Star in Ursa Major

Magnitude 3.8^m DoubleStar Ursa Major (UMa) Visible

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1Physical Properties

Magnitude 3.80

Range 3.71 - 3.83

Period 3.8 hours

Variable Type Delta Scuti (Pulsating)

Spectral Type F0IV subgiant

Star Color Yellow-white (B-V 0.29)

Distance 116 ly

2Position & Identifiers

RA 09h 50m 59.4s

Dec +59° 02' 19.0"

Constellation Ursa Major (UMa)

HR 3888

HIP 48319

HD 84999

SAO 27401

Bayer Upsilon

Flamsteed 29 UMa

Variable ID Ups UMa

Double Cat 7534

SIMBAD

3How easy to split?

Primary 3.8 mag Companion 11.3 mag Separation 11.9″

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

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)

5Light Curve

6Multiple Star System

Separation 11.9″

Companion Mag 11.3

Companion Sp M0

Position Angle 297°

Star Colors A: Yellow-white B: Red

Discoverer STT 521

Notes

CPM.

Separation over time

Measured 1855 → 2023 (168 y)

Separation drift 11.1" → 11.9" (+0.80")

Rate +0.0048" / y

PA drift 294° → 297° (+3°, +0.018°/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.