When is the best time to observe Iota Cassiopeiae?

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

Where is Iota Cassiopeiae located in the sky?

Iota Cassiopeiae lies in the constellation Cassiopeia at right ascension 02h 29m and declination +67° 24′.

What telescope do I need to split Iota Cassiopeiae?

Splitting Iota Cassiopeiae requires an aperture of roughly 100 mm or larger — the components are separated by about 3.0″ at magnitudes near 4.5. Larger apertures and steady seeing help resolve the pair cleanly.

Iota Cassiopeiae — Double Star in Cassiopeia

Observable Double Star Excellent (62/100)

Sep: 3.0", Companion: mag 6.9

Magnitude 4.5^m DoubleStar Cassiopeia (Cas) Visible

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Observe

1Physical Properties

Magnitude 4.52

Range 4.45 - 4.53

Period 41.8 hours

Variable Type Alpha2 CVn (Magnetic Rotating)

Spectral Type A5pSr

Star Color Yellow-white (B-V 0.12)

Distance 142 ly

2Position & Identifiers

RA 02h 29m 04.0s

Dec +67° 24' 09.0"

Constellation Cassiopeia (Cas)

HR 707

HIP 11569

HD 15089

SAO 12298

Bayer Iota

Variable ID Iot Cas

Double Cat 1860

SIMBAD

3How easy to split?

Primary 4.5 mag Companion 6.9 mag Separation 3.0″

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Telescope	Bortle 3	Bortle 4	Bortle 5
80 mm refractor 80mm refr.	Hard+	Hard+	Hard+
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)

5Light Curve

6Multiple Star System Quadruple C,D: optical

Components 4 (quadruple)

Component IDs AB

Separation 3.0″

Companion Mag 6.9

Companion Sp F9V

Position Angle 231°

Star Colors A: Yellow-white B: Yellow

Discoverer STF 262

Notes

AB 4.64 A3Vp, 6.89 F5, 840y, a = 2.27". A* 4.64 A5p, 52.4y, a = 0.113". Unresolved by speckle interferometry. | ABxC 4.51 A5p, 8.40 G7V, probably physical, 6.706" periastron for parabolic orbit. vsini of C =<50k/s.

Separation over time

Measured 1782 → 2022 (240 y)

Separation drift 1.5" → 3.0" (+1.50")

Rate +0.0063" / y

PA drift 290° → 231° (-59°, -0.246°/y)

Slow change over generations — observable in lifetime comparisons.

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.