When is the best time to observe 12 Ceti?

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

Where is 12 Ceti located in the sky?

12 Ceti lies in the constellation Cetus at right ascension 00h 30m and declination -03° 57′.

What telescope do I need to split 12 Ceti?

Splitting 12 Ceti requires an aperture of roughly 60 mm or larger — the components are separated by about 12.0″ at magnitudes near 5.7. The companion is about 4.5 magnitudes fainter, so glare from the primary — not separation — sets the minimum aperture. Larger apertures and steady seeing help resolve the pair cleanly.

12 Ceti — Double Star in Cetus

Magnitude 5.7^m DoubleStar Cetus (Cet) Visible

Star Map + List + Plan Star Hop

Observe

1Physical Properties

Magnitude 5.72

Spectral Type M0III giant

Star Color Red (B-V 1.56)

2Position & Identifiers

RA 00h 30m 02.4s

Dec -03° 57' 26.0"

Constellation Cetus (Cet)

HR 117

HIP 2353

HD 2637

SAO 128791

Flamsteed 12 Cet

Double Cat 410

SIMBAD

3How easy to split?

Primary 5.7 mag Companion 10.2 mag Separation 12.0″

Sign in and configure your equipment and default location to see a personalized row.

Telescope	Bortle 3	Bortle 4	Bortle 5
80 mm refractor 80mm refr.	Medium+	Medium	Hard+
150 mm Newton 150mm Newt.	Easy	Medium+	Medium+
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

Set a location in User Settings to see visibility data.

Best season Aug – Oct (peak: Sep)

5Multiple Star System B,C: optical

Separation 12.0″

Companion Mag 10.2

Position Angle 202°

Star Colors A: Red

Discoverer HJ 322

Notes

Optical.

Separation over time

Measured 1827 → 2015 (188 y)

Separation drift 8.0" → 12.0" (+4.00")

Rate +0.0213" / y

PA drift 170° → 202° (+32°, +0.170°/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.