When is the best time to observe Sigma Cancri?

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

Where is Sigma Cancri located in the sky?

Sigma Cancri lies in the constellation Cancer at right ascension 08h 60m and declination +32° 25′.

What telescope do I need to split Sigma Cancri?

Splitting Sigma Cancri requires an aperture of roughly 60 mm or larger — the components are separated by about 90.3″ at magnitudes near 5.2. The companion is about 3.8 magnitudes fainter, so glare from the primary — not separation — sets the minimum aperture. Larger apertures and steady seeing help resolve the pair cleanly.

Sigma Cancri — Double Star in Cancer

HIP 44154; Sigma3 Cancri; 64 Cancri

Observable Double Star Good (47/100)

Sep: 90.3", Companion: mag 9.0

Magnitude 5.2^m DoubleStar Cancer (Cnc) Visible

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Observe

1Physical Properties

Magnitude 5.20

Spectral Type G8III giant

Star Color Orange (B-V 0.93)

2Position & Identifiers

RA 08h 59m 32.6s

Dec +32° 25' 07.0"

Constellation Cancer (Cnc)

HR 3575

HIP 44154

HD 76813

SAO 61177

Bayer Sigma3

Flamsteed 64 Cnc

SIMBAD Wikipedia

3How easy to split?

Primary 5.2 mag Companion 9.0 mag Separation 90.3″

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Telescope	Bortle 3	Bortle 4	Bortle 5
80 mm refractor 80mm refr.	Easy	Medium+	Medium+
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 Dec – Feb (peak: Jan)

5Multiple Star System

Separation 90.3″

Companion Mag 9.0

Position Angle 294°

Star Colors A: Orange

Discoverer SHJ 100

Separation over time

Measured 1782 → 2013 (231 y)

Separation drift 85.8" → 90.3" (+4.50")

Rate +0.0195" / y

PA drift 295° → 294° (-1°, -0.004°/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.