When is the best time to observe Phi Cassiopeiae?

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

Where is Phi Cassiopeiae located in the sky?

Phi Cassiopeiae lies in the constellation Cassiopeia at right ascension 01h 20m and declination +58° 14′.

What telescope do I need to split Phi Cassiopeiae?

Splitting Phi Cassiopeiae requires an aperture of roughly 60 mm or larger — the components are separated by about 134.1″ at magnitudes near 5.0. Larger apertures and steady seeing help resolve the pair cleanly.

Phi Cassiopeiae — Double Star in Cassiopeia

Observable Double Star Good (47/100)

Sep: 134.1", Companion: mag 7.0

Magnitude 5.0^m DoubleStar Cassiopeia (Cas) Visible

Star Map + List + Plan

Observe

1Physical Properties

Magnitude 4.98

Spectral Type F0Ia supergiant

Star Color Orange (B-V 0.68)

2Position & Identifiers

RA 01h 20m 04.9s

Dec +58° 13' 54.0"

Constellation Cassiopeia (Cas)

HR 382

HIP 6242

HD 7927

SAO 22191

Bayer Phi

Flamsteed 34 Cas

Double Cat 1073

SIMBAD

3How easy to split?

Primary 5.0 mag Companion 7.0 mag Separation 134.1″

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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 Sep – Nov (peak: Oct)

5Multiple Star System Quintuple

Components 5 (quintuple)

Component IDs AC

Separation 134.1″

Companion Mag 7.0

Position Angle 231°

Star Colors A: Orange

Discoverer H 3 23

Notes

ADS 1073, quintuple system: A = NGC 457 #136; B, 12.3v at 49"; C = NGC 457 #131 = HD 7902, 6.99V, +0.42(B-V), | -0.38(U-B), B5Ia at 134", vsini =<25k/s; D, 10.19V, +0.29(B-V), -0.47(U-B) at 179"; E, 10.63V, +0.28(B-V), -0.52(U-B) at | 170".

Separation over time

Measured 1903 → 2016 (113 y)

Separation drift 133.8" → 134.1" (+0.30")

Rate +0.0027" / y

PA drift 231° → 231° (+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.