When is the best time to observe HIP 77390?

HIP 77390 is best observed from April through June, with peak visibility during May when it transits around midnight in the Northern Hemisphere.

Where is HIP 77390 located in the sky?

HIP 77390 lies in the constellation Triangulum Australe at right ascension 15h 48m and declination -65° 27′.

What telescope do I need to split HIP 77390?

Splitting HIP 77390 requires an aperture of roughly 150 mm or larger — the components are separated by about 1.7″ at magnitudes near 6.2. Larger apertures and steady seeing help resolve the pair cleanly.

HIP 77390 — Double Star in Triangulum Australe

Magnitude 6.2^m DoubleStar Triangulum Australe (TrA) Visible

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Observe

1Physical Properties

Magnitude 6.18

Spectral Type A5III-IV giant

Star Color Yellow-white (B-V 0.22)

2Position & Identifiers

RA 15h 47m 53.6s

Dec -65° 26' 33.0"

Constellation Triangulum Australe (TrA)

HR 5851

HIP 77390

HD 140484

SIMBAD

3How easy to split?

Primary 6.2 mag Companion 6.4 mag Separation 1.7″

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Telescope	Bortle 3	Bortle 4	Bortle 5
80 mm refractor 80mm refr.	Hard	Hard	Hard
150 mm Newton 150mm Newt.	Medium	Medium	Medium
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

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Best season Apr – Jun (peak: May)

5Multiple Star System

Separation 1.7″

Companion Mag 6.4

Position Angle 145°

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

Discoverer RMK 20

Notes

CPM with HR 5852. Combined mag. and colors, 5.53V, +0.23(B-V), +0.10(U-B).

Separation over time

Measured 1835 → 2016 (181 y)

Separation drift 2.4" → 1.7" (-0.70")

Rate -0.0039" / y

PA drift 156° → 145° (-11°, -0.061°/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.