When is the best time to observe 90 Leonis?

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

Where is 90 Leonis located in the sky?

90 Leonis lies in the constellation Leo at right ascension 11h 35m and declination +16° 48′.

What telescope do I need to split 90 Leonis?

Splitting 90 Leonis requires an aperture of roughly 100 mm or larger — the components are separated by about 3.1″ at magnitudes near 6.0. Larger apertures and steady seeing help resolve the pair cleanly.

90 Leonis — Double Star in Leo

Observable Double Star Good (59/100)

Sep: 3.1", Companion: mag 7.3

Magnitude 6.0^m DoubleStar Leo Visible

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Observe

1Physical Properties

Magnitude 5.95

Spectral Type B4V

Star Color Blue (B-V -0.16)

Distance 1,087 ly

2Position & Identifiers

RA 11h 34m 42.5s

Dec +16° 47' 49.0"

Constellation Leo

HR 4456

HIP 56473

HD 100600

SAO 99673

Flamsteed 90 Leo

Double Cat 8220

SIMBAD

3How easy to split?

Primary 6.0 mag Companion 7.3 mag Separation 3.1″

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Telescope	Bortle 3	Bortle 4	Bortle 5
80 mm refractor 80mm refr.	Medium	Medium	Medium
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 Feb – Apr (peak: Mar)

5Multiple Star System Triple

Components 3 (triple)

Component IDs AB

Separation 3.1″

Companion Mag 7.3

Companion Sp B9V

Position Angle 209°

Star Colors A: Blue B: Blue-white

Discoverer STF1552

Notes

AB binary. Combined mag., colors. B is B6. C, 9.64V F5 at 63".

Separation over time

Measured 1782 → 2018 (236 y)

Separation drift 3.0" → 3.1" (+0.10")

Rate +0.0004" / y

PA drift 209° → 209° (+0°, +0.000°/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.