When is the best time to observe Kappa Lupi?

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

Where is Kappa Lupi located in the sky?

Kappa Lupi lies in the constellation Lupus at right ascension 15h 12m and declination -48° 44′.

What telescope do I need to split Kappa Lupi?

Splitting Kappa Lupi requires an aperture of roughly 60 mm or larger — the components are separated by about 26.3″ at magnitudes near 3.9. Larger apertures and steady seeing help resolve the pair cleanly.

Kappa Lupi — Double Star in Lupus

HIP 74376; Kappa1 Lupi

Observable Double Star Excellent (62/100)

Sep: 26.3", Companion: mag 5.5

Magnitude 3.9^m DoubleStar Lupus (Lup) Visible

Star Map + List + Plan

About Kappa Lup

Description

Kappa Lupi is a B-type main-sequence star of spectral class B9.5 Vne about 180 light-years away. The "e" designation indicates spectral emission lines, a hallmark of the Be-type class. Kappa Lupi is a Be star with an occasional gas decretion disk that produces hydrogen emission features. It shines at magnitude 3.87.

Observing Tips

Kappa Lupi sits in the middle portion of the Lupus constellation, in the southern sky. From southern latitudes it is easily visible as a blue-white naked-eye point. Best observed April through August from the southern hemisphere.

History

Kappa Lupi retains its Bayer designation in current IAU catalogs.

Fun Facts

Be stars like Kappa Lupi are notable for their circumstellar gas disks that appear and disappear over months to years. These disks are fed by matter ejected from the rapidly-rotating stellar surface, producing variable hydrogen emission lines that can shift in strength noticeably over time.

Observe

1Physical Properties

Magnitude 3.87

Spectral Type B9.5Vne

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

Distance 180 ly

2Position & Identifiers

RA 15h 11m 56.1s

Dec -48° 44' 16.0"

Constellation Lupus (Lup)

HR 5646

HIP 74376

HD 134481

SAO 225525

Bayer Kappa1

SIMBAD Wikipedia

3How easy to split?

Primary 3.9 mag Companion 5.5 mag Separation 26.3″

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

Set a location in User Settings to see visibility data.

Best season Apr – Jun (peak: May)

5Multiple Star System

Separation 26.3″

Companion Mag 5.5

Companion Sp A5V

Position Angle 143°

Star Colors A: Blue-white B: Yellow-white

Discoverer DUN 177

Notes

CPM with HR 5647.

Separation over time

Measured 1826 → 2020 (194 y)

Separation drift 28.9" → 26.3" (-2.60")

Rate -0.0134" / y

PA drift 146° → 143° (-3°, -0.015°/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.