When is the best time to observe Kappa Leonis?

Kappa Leonis is best observed from January through March, with peak visibility during February when it transits around midnight in the Northern Hemisphere.

Where is Kappa Leonis located in the sky?

Kappa Leonis lies in the constellation Leo at right ascension 09h 25m and declination +26° 11′.

What telescope do I need to split Kappa Leonis?

Splitting Kappa Leonis requires an aperture of roughly 390 mm or larger — the components are separated by about 2.1″ at magnitudes near 4.5. The companion is about 5.2 magnitudes fainter, so glare from the primary — not separation — sets the minimum aperture. Larger apertures and steady seeing help resolve the pair cleanly.

Kappa Leonis — Double Star in Leo

Magnitude 4.5^m DoubleStar Leo Visible

Star Map + List + Plan

Observe

1Physical Properties

Magnitude 4.46

Spectral Type K2III giant

Star Color Red (B-V 1.23)

2Position & Identifiers

RA 09h 24m 39.3s

Dec +26° 10' 56.0"

Constellation Leo

HR 3731

HIP 46146

HD 81146

SAO 80807

Bayer Kappa

Flamsteed 1 Leo

Double Cat 7351

SIMBAD

3How easy to split?

Primary 4.5 mag Companion 9.7 mag Separation 2.1″

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

Easy Medium Hard Very hard Impossible

Bortle 3 = rural · 4 = outer suburbs · 5 = suburbs

To reach "Medium" at Bortle 3, you'd need at least a 390 mm reflector.

4Visibility

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Best season Jan – Mar (peak: Feb)

5Multiple Star System Triple C: optical

Components 3 (triple)

Component IDs AB

Separation 2.1″

Companion Mag 9.7

Position Angle 218°

Star Colors A: Red

Discoverer BU 105

Notes

AB binary.

Separation over time

Measured 1873 → 2016 (143 y)

Separation drift 2.0" → 2.1" (+0.10")

Rate +0.0007" / y

PA drift 210° → 218° (+8°, +0.056°/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.