When is the best time to observe Phi Ophiuchi?

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

Where is Phi Ophiuchi located in the sky?

Phi Ophiuchi lies in the constellation Ophiuchus at right ascension 16h 31m and declination -16° 37′.

What telescope do I need to split Phi Ophiuchi?

Splitting Phi Ophiuchi requires an aperture of roughly 60 mm or larger — the components are separated by about 119.4″ at magnitudes near 4.3. The companion is about 6.5 magnitudes fainter, so glare from the primary — not separation — sets the minimum aperture. Larger apertures and steady seeing help resolve the pair cleanly.

Phi Ophiuchi — Double Star in Ophiuchus

DoubleStar Ophiuchus (Oph) Visible

Star Map + List + Plan

Observe

1Physical Properties

Magnitude 4.28

Spectral Type G8+IIIa

Star Color Orange (B-V 0.92)

Distance 233 ly

2Position & Identifiers

RA 16h 31m 08.3s

Dec -16° 36' 46.0"

Constellation Ophiuchus (Oph)

HR 6147

HIP 80894

HD 148786

Bayer Phi

Flamsteed 8 Oph

Double Cat 10086

SIMBAD

3How easy to split?

Primary 4.3 mag Companion 10.8 mag Separation 119.4″

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

Components 3 (triple)

Component IDs AC

Separation 119.4″

Companion Mag 10.8

Position Angle 320°

Star Colors A: Orange

Discoverer BU 626

Separation over time

Measured 1904 → 2015 (111 y)

Separation drift 120.0" → 119.4" (-0.60")

Rate -0.0054" / y

PA drift 318° → 320° (+2°, +0.018°/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.