When is the best time to observe 2 Cassiopeiae?

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

Where is 2 Cassiopeiae located in the sky?

2 Cassiopeiae lies in the constellation Cassiopeia at right ascension 23h 10m and declination +59° 20′.

What telescope do I need to split 2 Cassiopeiae?

Splitting 2 Cassiopeiae requires an aperture of roughly 60 mm or larger — the components are separated by about 167.2″ at magnitudes near 5.7. Larger apertures and steady seeing help resolve the pair cleanly.

2 Cassiopeiae — Double Star in Cassiopeia

Observable Double Star Good (43/100)

Sep: 167.2", Companion: mag 8.2

DoubleStar Cassiopeia (Cas) Visible

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Observe

1Physical Properties

Magnitude 5.70

Spectral Type A5III

Star Color Yellow-white (B-V 0.33)

2Position & Identifiers

RA 23h 09m 44.1s

Dec +59° 19' 59.0"

Constellation Cassiopeia (Cas)

HR 8822

HIP 114365

HD 218753

Flamsteed 2 Cas

Variable ID Var?

Double Cat 16556

SIMBAD

3How easy to split?

Primary 5.7 mag Companion 8.2 mag Separation 167.2″

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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 Aug – Oct (peak: Sep)

5Multiple Star System 8 components

Components 8

Component IDs AC

Separation 167.2″

Companion Mag 8.2

Position Angle 163°

Star Colors A: Yellow-white

Discoverer S 823

Notes

C, 8.14V, +0.15(B-V), -0.38(U-B), A, HD 218780.

Separation over time

Measured 1824 → 2015 (191 y)

Separation drift 167.2" → 167.2" (+0.00")

Rate +0.0000" / y

PA drift 163° → 163° (+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.