When is the best time to observe Xi Scorpii?

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

Where is Xi Scorpii located in the sky?

Xi Scorpii lies in the constellation Scorpius at right ascension 16h 04m and declination -11° 22′.

What telescope do I need to split Xi Scorpii?

Splitting Xi Scorpii requires an aperture of roughly 150 mm or larger — the components are separated by about 1.2″ at magnitudes near 4.8. Larger apertures and steady seeing help resolve the pair cleanly.

Xi Scorpii — Double Star in Scorpius

HIP 78738; Xi Scorpii

Observable Double Star Fair (32/100)

Sep: 1.2", Companion: mag 4.9

Magnitude 4.8^m DoubleStar Scorpius (Sco) Visible

Star Map + List + Plan

Observe

1Physical Properties

Magnitude 4.77

Spectral Type F5IV subgiant

Star Color Yellow (B-V 0.47)

Distance 68 ly

2Position & Identifiers

RA 16h 04m 22.1s

Dec -11° 22' 23.0"

Constellation Scorpius (Sco)

HR 5978

HIP 78738

HD 144087

SAO 159668

Bayer Xi

Double Cat 9909

SIMBAD Wikipedia

3How easy to split?

Primary 4.8 mag Companion 4.9 mag Separation 1.2″

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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.	Hard+	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

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Best season Apr – Jun (peak: May)

5Multiple Star System Quintuple

Components 5 (quintuple)

Component IDs AB

Separation 1.2″

Companion Mag 4.9

Companion Sp F5IV

Position Angle 17°

Star Colors A: Yellow B: Yellow-white

Discoverer STF1998

Notes

Quintuple system ADS 9909A-C is CPM with ADS 9910, 7.4 G8V, 8.1K0V sep. 11" at 281" from ADS 9909A. ADS 9909AB 4.9 F5IV, | 4.9 F5IV, 45.69y, a = 0.720". Combined mag. 4.16V, combined colors. ADS 9909C, 7.30V, +0.75(B-V), dG7 at 7", physical.

Separation over time

Measured 1825 → 2023 (198 y)

Separation drift 1.2" → 1.2" (+0.00")

Rate +0.0000" / y

PA drift 356° → 17° (+21°, +0.106°/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.