When is the best time to observe Nu Canis Majoris?

Nu Canis Majoris is best observed from November through January, with peak visibility during December when it transits around midnight in the Northern Hemisphere.

Where is Nu Canis Majoris located in the sky?

Nu Canis Majoris lies in the constellation Canis Major at right ascension 06h 36m and declination -18° 40′.

What telescope do I need to split Nu Canis Majoris?

Splitting Nu Canis Majoris requires an aperture of roughly 60 mm or larger — the components are separated by about 17.4″ at magnitudes near 5.7. Larger apertures and steady seeing help resolve the pair cleanly.

Nu Canis Majoris — Double Star in Canis Major

HIP 31564; Nu Canis Majoris; 6 Canis Majoris

Observable Double Star Excellent (64/100)

Sep: 17.4", Companion: mag 7.4

Magnitude 5.7^m DoubleStar Canis Major (CMa) Visible

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Observe

1Physical Properties

Magnitude 5.70

Spectral Type G8III+F3IV-V giant

Star Color Orange (B-V 0.85)

2Position & Identifiers

RA 06h 36m 22.8s

Dec -18° 39' 36.0"

Constellation Canis Major (CMa)

HR 2423

HIP 31564

HD 47138

SAO 151694

Bayer Nu

Flamsteed 6 CMa

Double Cat 5253

SIMBAD Wikipedia

3How easy to split?

Primary 5.7 mag Companion 7.4 mag Separation 17.4″

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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 Nov – Jan (peak: Dec)

5Multiple Star System

Separation 17.4″

Companion Mag 7.4

Position Angle 264°

Star Colors A: Orange

Discoverer SHJ 73

Notes

CPM. Companion 7.65V, +0.32(B-V), +0.02(U-B), F2V.

Separation over time

Measured 1782 → 2019 (237 y)

Separation drift 18.3" → 17.4" (-0.90")

Rate -0.0038" / y

PA drift 270° → 264° (-6°, -0.025°/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.