When is the best time to observe Mu Crucis?

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

Where is Mu Crucis located in the sky?

Mu Crucis lies in the constellation Crux at right ascension 12h 55m and declination -57° 11′.

What telescope do I need to split Mu Crucis?

Splitting Mu Crucis requires an aperture of roughly 60 mm or larger — the components are separated by about 34.5″ at magnitudes near 4.0. Larger apertures and steady seeing help resolve the pair cleanly.

Mu Crucis — Double Star in Crux

Mu Cru (BS4898)

Observable Double Star Excellent (66/100)

Sep: 34.5", Companion: mag 5.0

Magnitude 4.0^m DoubleStar Crux (Cru) Visible

Star Map + List + Plan

Observe

1Physical Properties

Magnitude 4.03

Spectral Type B2IV-V subgiant

Star Color Blue (B-V -0.17)

2Position & Identifiers

RA 12h 54m 35.6s

Dec -57° 10' 40.0"

Constellation Crux (Cru)

HR 4898

HIP 63003

HD 112092

SAO 240366

Bayer Mu

SIMBAD Wikipedia

3How easy to split?

Primary 4.0 mag Companion 5.0 mag Separation 34.5″

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Telescope	Bortle 3	Bortle 4	Bortle 5
80 mm refractor 80mm refr.	Easy	Easy	Easy
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 Feb – Apr (peak: Mar)

5Multiple Star System

Separation 34.5″

Companion Mag 5.0

Position Angle 17°

Star Colors A: Blue B: Blue-white

Discoverer DUN 126

Notes

CPM with HR 4899.

Separation over time

Measured 1826 → 2020 (194 y)

Separation drift 35.9" → 34.5" (-1.40")

Rate -0.0072" / y

PA drift 10° → 17° (+7°, +0.036°/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.