When is the best time to observe 30 Eridani?

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

Where is 30 Eridani located in the sky?

30 Eridani lies in the constellation Eridanus at right ascension 03h 53m and declination -05° 22′.

What telescope do I need to split 30 Eridani?

Splitting 30 Eridani requires an aperture of roughly 80 mm or larger — the components are separated by about 8.3″ at magnitudes near 5.5. The companion is about 4.9 magnitudes fainter, so glare from the primary — not separation — sets the minimum aperture. Larger apertures and steady seeing help resolve the pair cleanly.

30 Eridani — Double Star in Eridanus

Magnitude 5.5^m DoubleStar Eridanus (Eri) Visible

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Observe

1Physical Properties

Magnitude 5.48

Spectral Type B8V

Star Color Blue-white (B-V -0.10)

Distance 181 ly

2Position & Identifiers

RA 03h 52m 41.6s

Dec -05° 21' 41.0"

Constellation Eridanus (Eri)

HR 1202

HIP 18141

HD 24388

SAO 130789

Flamsteed 30 Eri

Double Cat 2832

SIMBAD

3How easy to split?

Primary 5.5 mag Companion 10.4 mag Separation 8.3″

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

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

Separation 8.3″

Companion Mag 10.3

Position Angle 134°

Star Colors A: Blue-white B: Yellow

Discoverer HJ 338

Notes

Companion F4V, optical.

Separation over time

Measured 1827 → 2000 (173 y)

Separation drift 10.0" → 8.3" (-1.70")

Rate -0.0098" / y

PA drift 135° → 134° (-1°, -0.006°/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.