When is the best time to observe 66 Ceti?

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

Where is 66 Ceti located in the sky?

66 Ceti lies in the constellation Cetus at right ascension 02h 13m and declination -02° 24′.

What telescope do I need to split 66 Ceti?

Splitting 66 Ceti requires an aperture of roughly 60 mm or larger — the components are separated by about 16.8″ at magnitudes near 5.5. Larger apertures and steady seeing help resolve the pair cleanly.

66 Ceti — Double Star in Cetus

Observable Double Star Good (57/100)

Sep: 16.8", Companion: mag 7.7

Magnitude 5.5^m DoubleStar Cetus (Cet) Visible

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Observe

1Physical Properties

Magnitude 5.54

Spectral Type F8V

Star Color Yellow (B-V 0.57)

Distance 72 ly

2Position & Identifiers

RA 02h 12m 47.5s

Dec -02° 23' 37.0"

Constellation Cetus (Cet)

HR 650

HIP 10305

HD 13612

SAO 129752

Flamsteed 66 Cet

Double Cat 1703

SIMBAD

3How easy to split?

Primary 5.5 mag Companion 7.7 mag Separation 16.8″

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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 Triple optical

Components 3 (triple)

Component IDs AB

Separation 16.8″

Companion Mag 7.7

Companion Sp G1V

Position Angle 235°

Star Colors A: Yellow B: Yellow

Discoverer STF 231

Notes

AB binary; B, dG4; C, 11.5v at 173".

Separation over time

Measured 1783 → 2024 (241 y)

Separation drift 16.9" → 16.8" (-0.10")

Rate -0.0004" / y

PA drift 235° → 235° (+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.