When is the best time to observe 115 Tauri?

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

Where is 115 Tauri located in the sky?

115 Tauri lies in the constellation Taurus at right ascension 05h 27m and declination +17° 58′.

What telescope do I need to split 115 Tauri?

Splitting 115 Tauri requires an aperture of roughly 60 mm or larger — the components are separated by about 10.1″ at magnitudes near 5.4. The companion is about 5.7 magnitudes fainter, so glare from the primary — not separation — sets the minimum aperture. Larger apertures and steady seeing help resolve the pair cleanly.

115 Tauri — Double Star in Taurus

Magnitude 5.4^m DoubleStar Taurus (Tau) Visible

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Observe

1Physical Properties

Magnitude 5.42

Spectral Type B5V

Star Color Blue (B-V -0.10)

2Position & Identifiers

RA 05h 27m 10.1s

Dec +17° 57' 44.0"

Constellation Taurus (Tau)

HR 1808

HIP 25499

HD 35671

SAO 94554

Flamsteed 115 Tau

Double Cat 4038

SIMBAD

3How easy to split?

Primary 5.4 mag Companion 11.1 mag Separation 10.1″

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Telescope	Bortle 3	Bortle 4	Bortle 5
80 mm refractor 80mm refr.	Hard+	Hard	V. hard+
150 mm Newton 150mm Newt.	Medium+	Medium	Medium
Celestron C8 (203 mm SCT) C8 203mm	Easy	Medium+	Medium

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 Quadruple

Components 4 (quadruple)

Component IDs O

Separation 10.1″

Companion Mag 11.1

Companion Sp F8V

Position Angle 307°

Star Colors A: Blue B: Yellow

Discoverer STT 107

Notes

ADS 4038A is occultation double. B and C are 10.1v at 305" and 11.8v at 343".

Separation over time

Measured 1843 → 2022 (179 y)

Separation drift 10.7" → 10.1" (-0.60")

Rate -0.0034" / y

PA drift 317° → 307° (-10°, -0.056°/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.