When is the best time to observe Upsilon Librae?

Upsilon Librae is best observed from April through June, with peak visibility during May when it transits around midnight in the Northern Hemisphere.

Where is Upsilon Librae located in the sky?

Upsilon Librae lies in the constellation Libra at right ascension 15h 37m and declination -28° 08′.

What telescope do I need to split Upsilon Librae?

Splitting Upsilon Librae requires an aperture of roughly 530 mm or larger — the components are separated by about 3.5″ at magnitudes near 3.6. The companion is about 7.2 magnitudes fainter, so glare from the primary — not separation — sets the minimum aperture. Larger apertures and steady seeing help resolve the pair cleanly.

Upsilon Librae — Double Star in Libra

Magnitude 3.6^m DoubleStar Libra (Lib) Visible

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1Physical Properties

Magnitude 3.58

Spectral Type K3.5III giant

Star Color Red (B-V 1.38)

Distance 224 ly

2Position & Identifiers

RA 15h 37m 01.5s

Dec -28° 08' 06.0"

Constellation Libra (Lib)

HR 5794

HIP 76470

HD 139063

SAO 183619

Bayer Upsilon

Flamsteed 39 Lib

Double Cat 9705

SIMBAD

3How easy to split?

Primary 3.6 mag Companion 10.8 mag Separation 3.5″

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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.	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 530 mm reflector.

4Visibility

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Best season Apr – Jun (peak: May)

5Multiple Star System

Separation 3.5″

Companion Mag 10.8

Position Angle 165°

Star Colors A: Red

Discoverer I 1271

Separation over time

Measured 1925 → 2016 (91 y)

Separation drift 3.0" → 3.5" (+0.50")

Rate +0.0055" / y

PA drift 164° → 165° (+1°, +0.011°/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.