When is the best time to observe BU Circini?

BU Circini is best observed from March through May, with peak visibility during April when it transits around midnight in the Northern Hemisphere.

Where is BU Circini located in the sky?

BU Circini lies in the constellation Circinus at right ascension 14h 45m and declination -55° 36′.

What telescope do I need to split BU Circini?

Splitting BU Circini requires an aperture of roughly 60 mm or larger — the components are separated by about 69.0″ at magnitudes near 6.1. Larger apertures and steady seeing help resolve the pair cleanly.

BU Circini — Double Star in Circinus

DoubleStar Circinus (Cir) Visible

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Observe

1Physical Properties

Magnitude 6.10

Variable Type Beta Cephei (Pulsating)

Spectral Type B2III

Star Color Blue-white (B-V -0.06)

2Position & Identifiers

RA 14h 45m 10.9s

Dec -55° 36' 07.0"

Constellation Circinus (Cir)

HR 5488

HIP 72121

HD 129557

Variable ID BU Cir

SIMBAD

3How easy to split?

Primary 6.1 mag Companion 7.6 mag Separation 69.0″

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Telescope	Bortle 3	Bortle 4	Bortle 5
80 mm refractor 80mm refr.	Easy	Easy	Easy
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 Mar – May (peak: Apr)

5Multiple Star System

Separation 69.0″

Companion Mag 7.5

Position Angle 105°

Star Colors A: Blue-white B: Yellow-white

Discoverer DUN 169

Separation over time

Measured 1826 → 2015 (189 y)

Separation drift 71.8" → 69.0" (-2.80")

Rate -0.0148" / y

PA drift 107° → 105° (-2°, -0.011°/y)

Slow change over generations — observable in lifetime comparisons.

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.