When is the best time to observe 61 Ceti?

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

Where is 61 Ceti located in the sky?

61 Ceti lies in the constellation Cetus at right ascension 02h 04m and declination -00° 20′.

What telescope do I need to split 61 Ceti?

Splitting 61 Ceti requires an aperture of roughly 60 mm or larger — the components are separated by about 43.1″ at magnitudes near 5.9. The companion is about 4.8 magnitudes fainter, so glare from the primary — not separation — sets the minimum aperture. Larger apertures and steady seeing help resolve the pair cleanly.

61 Ceti — Double Star in Cetus

Magnitude 5.9^m DoubleStar Cetus (Cet) Visible

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Observe

1Physical Properties

Magnitude 5.93

Spectral Type G5II-III+G5V bright giant

Star Color Orange (B-V 0.88)

2Position & Identifiers

RA 02h 03m 48.2s

Dec -00° 20' 25.0"

Constellation Cetus (Cet)

HR 610

HIP 9631

HD 12641

SAO 129667

Flamsteed 61 Cet

Double Cat 1634

SIMBAD

3How easy to split?

Primary 5.9 mag Companion 10.8 mag Separation 43.1″

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Telescope	Bortle 3	Bortle 4	Bortle 5
80 mm refractor 80mm refr.	Medium	Hard+	Hard
150 mm Newton 150mm Newt.	Medium+	Medium+	Medium
Celestron C8 (203 mm SCT) C8 203mm	Easy	Medium+	Medium+

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 C: optical

Components 3 (triple)

Component IDs AB

Separation 43.1″

Companion Mag 10.8

Companion Sp G5V

Position Angle 194°

Star Colors A: Orange B: Orange

Discoverer H 5 102

Notes

ADS 1634AB CPM. B, G5V; C at 83" optical.

Separation over time

Measured 1782 → 2014 (232 y)

Separation drift 37.9" → 43.1" (+5.20")

Rate +0.0224" / y

PA drift 194° → 194° (+0°, +0.000°/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.