When is the best time to observe Beta Serpentis?

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

Where is Beta Serpentis located in the sky?

Beta Serpentis lies in the constellation Serpens at right ascension 15h 46m and declination +15° 25′.

What telescope do I need to split Beta Serpentis?

Splitting Beta Serpentis requires an aperture of roughly 60 mm or larger — the components are separated by about 30.3″ at magnitudes near 3.7. The companion is about 6.3 magnitudes fainter, so glare from the primary — not separation — sets the minimum aperture. Larger apertures and steady seeing help resolve the pair cleanly.

Beta Serpentis — Double Star in Serpens

Magnitude 3.7^m DoubleStar Serpens (Ser) Visible

Star Map + List + Plan

Observe

1Physical Properties

Magnitude 3.67

Spectral Type A1V

Star Color White (B-V 0.06)

Distance 155 ly

2Position & Identifiers

RA 15h 46m 11.3s

Dec +15° 25' 19.0"

Constellation Serpens (Ser)

HR 5867

HIP 77233

HD 141003

SAO 101725

Bayer Beta

Flamsteed 28 Ser

Double Cat 9778

SIMBAD

3How easy to split?

Primary 3.7 mag Companion 10.0 mag Separation 30.3″

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Telescope	Bortle 3	Bortle 4	Bortle 5
80 mm refractor 80mm refr.	Medium+	Medium	Hard+
150 mm Newton 150mm Newt.	Easy	Easy	Medium+
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 Apr – Jun (peak: May)

5Multiple Star System Quintuple C: optical

Components 5 (quintuple)

Component IDs AB

Separation 30.3″

Companion Mag 10.0

Companion Sp G0

Position Angle 264°

Star Colors A: White B: Yellow

Discoverer STF1970

Notes

B, 9.72V, +0.84(B-V), +0.68(U-B), K3V, CPM. C, 10.7v at 201". Also CPM with BD+15d2906 at 1642", itself a double, 8.4, | 10.5v sep. 6".

Separation over time

Measured 1781 → 2023 (242 y)

Separation drift 24.0" → 30.3" (+6.30")

Rate +0.0260" / y

PA drift 267° → 264° (-3°, -0.012°/y)

Apparent motion is significant on a human timescale — worth revisiting in a decade.

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.