When is the best time to observe Acubens?

Acubens is best observed from December through February, with peak visibility during January when it transits around midnight in the Northern Hemisphere.

Where is Acubens located in the sky?

Acubens lies in the constellation Cancer at right ascension 08h 58m and declination +11° 51′.

What telescope do I need to split Acubens?

Splitting Acubens requires an aperture of roughly 210 mm or larger — the components are separated by about 10.3″ at magnitudes near 4.2. The companion is about 7.6 magnitudes fainter, so glare from the primary — not separation — sets the minimum aperture. Larger apertures and steady seeing help resolve the pair cleanly.

Acubens — Double Star in Cancer

HIP 44066; Alpha Cancri; 65 Cancri

Magnitude 4.2^m DoubleStar Cancer (Cnc) Visible

Star Map + List + Plan

Observe

1Physical Properties

Magnitude 4.25

Spectral Type A5m

Star Color Yellow-white (B-V 0.14)

Distance 136 ly

2Position & Identifiers

RA 08h 58m 29.2s

Dec +11° 51' 28.0"

Constellation Cancer (Cnc)

HR 3572

HIP 44066

HD 76756

SAO 98267

Bayer Alpha

Flamsteed 65 Cnc

Double Cat 7115

SIMBAD Wikipedia

3How easy to split?

Primary 4.3 mag Companion 11.8 mag Separation 10.3″

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.	V. hard+	V. hard+	V. hard
150 mm Newton 150mm Newt.	Hard	Hard	Hard
Celestron C8 (203 mm SCT) C8 203mm	Hard+	Hard+	Hard+

Easy Medium Hard Very hard Impossible

Bortle 3 = rural · 4 = outer suburbs · 5 = suburbs

To reach "Medium" at Bortle 3, you'd need at least a 210 mm reflector.

4Visibility

Set a location in User Settings to see visibility data.

Best season Dec – Feb (peak: Jan)

5Multiple Star System Triple

Components 3 (triple)

Separation 10.3″

Companion Mag 11.8

Position Angle 321°

Star Colors A: Yellow-white

Discoverer HJ 110

Notes

ADS 7115A is questioned close double. Combined mag., colors, 5.0, 5.0v, sep. 0.1". B is 10.8v at 11", binary.

Separation over time

Measured 1825 → 2018 (193 y)

Separation drift 10.0" → 10.3" (+0.30")

Rate +0.0016" / y

PA drift 320° → 321° (+1°, +0.005°/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.