When is the best time to observe Chi Tauri?

Chi Tauri is best observed from October through December, with peak visibility during November when it transits around midnight in the Northern Hemisphere.

Where is Chi Tauri located in the sky?

Chi Tauri lies in the constellation Taurus at right ascension 04h 23m and declination +25° 38′.

What telescope do I need to split Chi Tauri?

Splitting Chi Tauri requires an aperture of roughly 60 mm or larger — the components are separated by about 19.4″ at magnitudes near 5.4. The companion is about 3.2 magnitudes fainter, so glare from the primary — not separation — sets the minimum aperture. Larger apertures and steady seeing help resolve the pair cleanly.

Chi Tauri — Double Star in Taurus

Observable Double Star Excellent (61/100)

Sep: 19.4", Companion: mag 8.5

Magnitude 5.4^m DoubleStar Taurus (Tau) Visible

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Observe

1Physical Properties

Magnitude 5.37

Spectral Type B9V

Star Color Blue-white (B-V -0.05)

2Position & Identifiers

RA 04h 22m 34.9s

Dec +25° 37' 45.0"

Constellation Taurus (Tau)

HR 1369

HIP 20430

HD 27638

SAO 76573

Bayer Chi

Flamsteed 59 Tau

Double Cat 3161

SIMBAD

3How easy to split?

Primary 5.4 mag Companion 8.5 mag Separation 19.4″

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Telescope	Bortle 3	Bortle 4	Bortle 5
80 mm refractor 80mm refr.	Easy	Easy	Medium+
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 Oct – Dec (peak: Nov)

5Multiple Star System Triple

Components 3 (triple)

Separation 19.4″

Companion Mag 8.5

Companion Sp F8V

Position Angle 25°

Star Colors A: Blue-white B: Yellow

Discoverer STF 528

Notes

CPM. Component A suspected occultation double; component B, G2V, strong lithium.

Separation over time

Measured 1822 → 2016 (194 y)

Separation drift 19.7" → 19.4" (-0.30")

Rate -0.0015" / y

PA drift 27° → 25° (-2°, -0.010°/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.