When is the best time to observe Eta Lupi?

Eta Lupi is best observed from April through June, with peak visibility during May when it transits around midnight in the Northern Hemisphere.

Where is Eta Lupi located in the sky?

Eta Lupi lies in the constellation Lupus at right ascension 16h 00m and declination -38° 24′.

What telescope do I need to split Eta Lupi?

Splitting Eta Lupi requires an aperture of roughly 60 mm or larger — the components are separated by about 14.8″ at magnitudes near 3.4. The companion is about 4.1 magnitudes fainter, so glare from the primary — not separation — sets the minimum aperture. Larger apertures and steady seeing help resolve the pair cleanly.

Eta Lupi — Double Star in Lupus

Observable Double Star Excellent (62/100)

Sep: 14.8", Companion: mag 7.5

Magnitude 3.4^m DoubleStar Lupus (Lup) Visible

Star Map + List + Plan

Observe

1Physical Properties

Magnitude 3.41

Spectral Type B2.5 IV subgiant

Star Color Blue (B-V -0.22)

Distance 442 ly

2Position & Identifiers

RA 16h 00m 07.3s

Dec -38° 23' 49.0"

Constellation Lupus (Lup)

HR 5948

HIP 78384

HD 143118

SAO 207208

Bayer Eta

SIMBAD

3How easy to split?

Primary 3.4 mag Companion 7.5 mag Separation 14.8″

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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 Apr – Jun (peak: May)

5Multiple Star System Triple D: optical

Components 3 (triple)

Component IDs AB

Separation 14.8″

Companion Mag 7.5

Position Angle 19°

Star Colors A: Blue B: Yellow-white

Discoverer RMK 21

Notes

AB binary. Companion A5Vp.

Separation over time

Measured 1834 → 2020 (186 y)

Separation drift 13.5" → 14.8" (+1.30")

Rate +0.0070" / y

PA drift 22° → 19° (-3°, -0.016°/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.