When is the best time to observe Upsilon Gruis?

Upsilon Gruis is best observed from August through October, with peak visibility during September when it transits around midnight in the Northern Hemisphere.

Where is Upsilon Gruis located in the sky?

Upsilon Gruis lies in the constellation Grus at right ascension 23h 07m and declination -38° 54′.

What telescope do I need to split Upsilon Gruis?

Splitting Upsilon Gruis requires an aperture of roughly 320 mm or larger — the components are separated by about 0.9″ at magnitudes near 5.6. Larger apertures and steady seeing help resolve the pair cleanly.

Upsilon Gruis — Double Star in Grus

Magnitude 5.6^m DoubleStar Grus (Gru) Visible

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Observe

1Physical Properties

Magnitude 5.61

Spectral Type A1V

Star Color White (B-V 0.01)

2Position & Identifiers

RA 23h 06m 53.6s

Dec -38° 53' 32.0"

Constellation Grus (Gru)

HR 8790

HIP 114132

HD 218242

SAO 214313

Bayer Upsilon

SIMBAD

3How easy to split?

Primary 5.6 mag Companion 8.2 mag Separation 0.9″

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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.	V. hard+	V. hard+	V. hard+
Celestron C8 (203 mm SCT) C8 203mm	Hard	Hard	Hard

Easy Medium Hard Very hard Impossible

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

To reach "Medium" at Bortle 3, you'd need at least a 320 mm reflector.

4Visibility

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Best season Aug – Oct (peak: Sep)

5Multiple Star System

Separation 0.9″

Companion Mag 8.2

Position Angle 205°

Star Colors A: White B: Yellow

Discoverer BU 773

Separation over time

Measured 1920 → 2009 (89 y)

Separation drift 1.2" → 0.90" (-0.30")

Rate -0.0034" / y

PA drift 212° → 205° (-7°, -0.079°/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.