When is the best time to observe Psi Cassiopeiae?

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

Where is Psi Cassiopeiae located in the sky?

Psi Cassiopeiae lies in the constellation Cassiopeia at right ascension 01h 26m and declination +68° 08′.

What telescope do I need to split Psi Cassiopeiae?

Splitting Psi Cassiopeiae requires an aperture of roughly 60 mm or larger — the components are separated by about 20.3″ at magnitudes near 4.7. The companion is about 4.4 magnitudes fainter, so glare from the primary — not separation — sets the minimum aperture. Larger apertures and steady seeing help resolve the pair cleanly.

Psi Cassiopeiae — Double Star in Cassiopeia

DoubleStar Cassiopeia (Cas) Visible

Star Map + List + Plan

Observe

1Physical Properties

Magnitude 4.74

Spectral Type K0III

Star Color Orange (B-V 1.05)

Distance 251 ly

2Position & Identifiers

RA 01h 25m 56.0s

Dec +68° 07' 48.0"

Constellation Cassiopeia (Cas)

HR 399

HIP 6692

HD 8491

Bayer Psi

Flamsteed 36 Cas

Double Cat 1129

SIMBAD

3How easy to split?

Primary 4.7 mag Companion 9.2 mag Separation 20.3″

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Telescope	Bortle 3	Bortle 4	Bortle 5
80 mm refractor 80mm refr.	Easy	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 Sep – Nov (peak: Oct)

5Multiple Star System Quadruple C,D: optical

Components 4 (quadruple)

Component IDs AC

Separation 20.3″

Companion Mag 9.2

Position Angle 127°

Star Colors A: Orange

Discoverer H 5 83

Notes

ADS 1129B, 13.5v, 3" CPM with A. Component C optical, 9.18V, +0.66 (B-V), +0.34(U-B), Am.

Separation over time

Measured 1782 → 2020 (238 y)

Separation drift 33.4" → 20.3" (-13.10")

Rate -0.0550" / y

PA drift 100° → 127° (+27°, +0.113°/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.