When is the best time to observe Tau Geminorum?

Tau Geminorum is best observed from December through February, with peak visibility during January when it transits around midnight in the Northern Hemisphere.

Where is Tau Geminorum located in the sky?

Tau Geminorum lies in the constellation Gemini at right ascension 07h 11m and declination +30° 15′.

What telescope do I need to split Tau Geminorum?

Splitting Tau Geminorum requires an aperture of roughly 790 mm or larger — the components are separated by about 1.8″ at magnitudes near 4.4. The companion is about 6.6 magnitudes fainter, so glare from the primary — not separation — sets the minimum aperture. Larger apertures and steady seeing help resolve the pair cleanly.

Tau Geminorum — Double Star in Gemini

Magnitude 4.4^m DoubleStar Gemini (Gem) Visible 1 Exoplanet

Star Map + List + Plan

Observe

1Physical Properties

Magnitude 4.41

Spectral Type K2-III

Star Color Orange (B-V 1.26) (reddened by dust)

Distance 466 ly

2Position & Identifiers

RA 07h 11m 08.4s

Dec +30° 14' 43.0"

Constellation Gemini (Gem)

HR 2697

HIP 34693

HD 54719

SAO 59858

Bayer Tau

Flamsteed 46 Gem

Double Cat 5846

SIMBAD

3How easy to split?

Primary 4.4 mag Companion 11.0 mag Separation 1.8″

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 790 mm reflector.

4Visibility

Set a location in User Settings to see visibility data.

Best season Dec – Feb (peak: Jan)

5Multiple Star System Triple C: optical

Components 3 (triple)

Component IDs AB

Separation 1.8″

Companion Mag 11.0

Position Angle 163°

Star Colors A: Orange (reddened by dust)

Discoverer BU 1009

Notes

AB CPM.

Separation over time

Measured 1881 → 2004 (123 y)

Separation drift 1.8" → 1.8" (+0.00")

Rate +0.0000" / y

PA drift 175° → 163° (-12°, -0.098°/y)

Essentially fixed on human timescales — the same view your grandchildren will see.

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.