When is the best time to observe HIP 81966?

HIP 81966 is best observed from April through June, with peak visibility during May when it transits around midnight in the Northern Hemisphere.

Where is HIP 81966 located in the sky?

HIP 81966 lies in the constellation Ara at right ascension 16h 45m and declination -53° 09′.

What telescope do I need to split HIP 81966?

Splitting HIP 81966 requires an aperture of roughly 60 mm or larger — the components are separated by about 28.1″ at magnitudes near 6.0. The companion is about 6.0 magnitudes fainter, so glare from the primary — not separation — sets the minimum aperture. Larger apertures and steady seeing help resolve the pair cleanly.

HIP 81966 — Double Star in Ara

Magnitude 6.0^m DoubleStar Ara Visible

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Observe

1Physical Properties

Magnitude 5.96

Spectral Type G8III giant

Star Color Red (B-V 1.26)

2Position & Identifiers

RA 16h 44m 39.8s

Dec -53° 09' 09.0"

Constellation Ara

HR 6207

HIP 81966

HD 150576

SAO 244106

SIMBAD

3How easy to split?

Primary 6.0 mag Companion 12.0 mag Separation 28.1″

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

Easy Medium Hard Very hard Impossible

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

4Visibility

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Best season Apr – Jun (peak: May)

5Multiple Star System

Separation 28.1″

Companion Mag 12.0

Position Angle 38°

Star Colors A: Red

Discoverer HDO 258

Separation over time

Measured 1891 → 2016 (125 y)

Separation drift 20.0" → 28.1" (+8.10")

Rate +0.0648" / y

PA drift 40° → 38° (-2°, -0.016°/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.