When is the best time to observe Rho Octantis?

Rho Octantis is best observed from April through June, with peak visibility during May when it transits around midnight in the Northern Hemisphere.

Where is Rho Octantis located in the sky?

Rho Octantis lies in the constellation Octans at right ascension 15h 43m and declination -84° 28′.

What telescope do I need to split Rho Octantis?

Splitting Rho Octantis requires an aperture of roughly 60 mm or larger — the components are separated by about 65.8″ at magnitudes near 5.6. The companion is about 6.1 magnitudes fainter, so glare from the primary — not separation — sets the minimum aperture. Larger apertures and steady seeing help resolve the pair cleanly.

Rho Octantis — Double Star in Octans

Magnitude 5.6^m DoubleStar Octans (Oct) Visible

Star Map + List + Plan Star Hop

Observe

1Physical Properties

Magnitude 5.57

Spectral Type A2V

Star Color White (B-V 0.11)

2Position & Identifiers

RA 15h 43m 16.8s

Dec -84° 27' 55.0"

Constellation Octans (Oct)

HR 5729

HIP 76996

HD 137333

SAO 258731

Bayer Rho

SIMBAD

3How easy to split?

Primary 5.6 mag Companion 11.6 mag Separation 65.8″

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

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 Apr – Jun (peak: May)

5Multiple Star System

Separation 65.8″

Companion Mag 11.6

Companion Sp K0

Position Angle 333°

Star Colors A: White B: Orange

Discoverer GRV1247

Separation over time

Measured 1896 → 2016 (120 y)

Separation drift 65.7" → 65.8" (+0.10")

Rate +0.0008" / y

PA drift 333° → 333° (+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.