When is the best time to observe Lambda Andromedae?

Lambda Andromedae is best observed from August through October, with peak visibility during September when it transits around midnight in the Northern Hemisphere.

Where is Lambda Andromedae located in the sky?

Lambda Andromedae lies in the constellation Andromeda at right ascension 23h 38m and declination +46° 27′.

What telescope do I need to split Lambda Andromedae?

Splitting Lambda Andromedae requires an aperture of roughly 60 mm or larger — the components are separated by about 211.4″ at magnitudes near 3.8. The companion is about 7.5 magnitudes fainter, so glare from the primary — not separation — sets the minimum aperture. Larger apertures and steady seeing help resolve the pair cleanly.

Lambda Andromedae — Double Star in Andromeda

DoubleStar Andromeda (And) Visible

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1Physical Properties

Magnitude 3.82

Range 3.65 - 4.05

Period 54 days

Variable Type RS CVn (Chromospherically Active)

Spectral Type G8IV k

Star Color Orange (B-V 1.01)

Distance 86 ly

2Position & Identifiers

RA 23h 37m 33.9s

Dec +46° 27' 29.0"

Constellation Andromeda (And)

HR 8961

HIP 116584

HD 222107

Bayer Lambda

Flamsteed 16 And

Variable ID Lam And

SIMBAD

3How easy to split?

Primary 3.8 mag Companion 11.3 mag Separation 211.4″

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

Easy Medium Hard Very hard Impossible

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

4Visibility

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Best season Aug – Oct (peak: Sep)

5Light Curve

6Multiple Star System Quadruple B: optical

Components 4 (quadruple)

Component IDs AC

Separation 211.4″

Companion Mag 11.3

Position Angle 77°

Star Colors A: Orange

Discoverer STT 600

Separation over time

Measured 1868 → 2015 (147 y)

Separation drift 222.2" → 211.4" (-10.80")

Rate -0.0735" / y

PA drift 93° → 77° (-16°, -0.109°/y)

Apparent motion is significant on a human timescale — worth revisiting in a decade.

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.

Eyepiece View

Telescope Eyepiece

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32x Dawes: 1.9″ TFOV: 1.6°

Seeing

Scale Realistic = true angular size

A: 3.8 · B: 11.3 · Sep: 211.4″ · PA: 77° · N up, E left

Resolved · Rayleigh: 2.3″ · Dawes: 1.9″ · Eff: 2.3″

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Size Comparison

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Spectral Classification

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Hertzsprung-Russell Diagram

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Stellar Lifecycle

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Blackbody Spectrum

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Stellar Absorption Spectrum

Simulated absorption spectrum based on spectral type. Hover over lines to identify elements.

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Stellar Fusion

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16Stellar Notes

Variable Star

RS 3.69 - 3.97V, 4.74 - 5.13B, 54.20d. Amp. and cycle length vary in period 3200d. Also 0.25m var. in period about | 50d. H and K emission correlated with 56d light period.

Spectroscopic Binary

20.5212d, K 6.6k/s, V0 +6.8k/s, asini 1.86. Radio binary. Unresolved by speckle interferometry. Possible radio | emitter.

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