When is the best time to observe Theta Virginis?

Theta Virginis is best observed from March through May, with peak visibility during April when it transits around midnight in the Northern Hemisphere.

Where is Theta Virginis located in the sky?

Theta Virginis lies in the constellation Virgo at right ascension 13h 10m and declination -05° 32′.

What telescope do I need to split Theta Virginis?

Splitting Theta Virginis requires an aperture of roughly 80 mm or larger — the components are separated by about 7.0″ at magnitudes near 4.4. The companion is about 5.0 magnitudes fainter, so glare from the primary — not separation — sets the minimum aperture. Larger apertures and steady seeing help resolve the pair cleanly.

Theta Virginis — Double Star in Virgo

Magnitude 4.4^m DoubleStar Virgo (Vir) Visible

Star Map + List + Plan

Observe

1Physical Properties

Magnitude 4.38

Spectral Type A1IV s+Am subgiant

Star Color Blue-white (B-V -0.01)

Distance 125 ly

2Position & Identifiers

RA 13h 09m 57.0s

Dec -05° 32' 20.0"

Constellation Virgo (Vir)

HR 4963

HIP 64238

HD 114330

SAO 139189

Bayer Theta

Flamsteed 51 Vir

Double Cat 8801

SIMBAD

3How easy to split?

Primary 4.4 mag Companion 9.4 mag Separation 7.0″

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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	Easy	Easy	Easy

Easy Medium Hard Very hard Impossible

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

4Visibility

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Best season Mar – May (peak: Apr)

5Multiple Star System Quadruple C: optical

Components 4 (quadruple)

Separation 7.0″

Companion Mag 9.4

Companion Sp B8V

Position Angle 342°

Star Colors A: Blue-white B: Blue-white

Discoverer STF1724

Notes

A is SB and speckle interferometric binary, third component 9.4v, sep. 7.1". B, 8.00V, +0.20(B-V), -0.09(U-B), CPM.

Separation over time

Measured 1782 → 2015 (233 y)

Separation drift 7.1" → 7.0" (-0.10")

Rate -0.0004" / y

PA drift 339° → 342° (+3°, +0.013°/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.

Eyepiece View

Telescope Eyepiece

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80x Dawes: 1.9″ TFOV: 0.6°

Seeing

Scale Realistic = true angular size

A: 4.4 · B: 9.4 · Sep: 7.0″ · PA: 342° · N up, E right

Resolved · Rayleigh: 2.3″ · Dawes: 1.9″ · Eff: 2.3″

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Size Comparison

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Compare Stars

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Spectral Classification

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Hertzsprung-Russell Diagram

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Read: The Hertzsprung-Russell Diagram — Reading Stars Like a Map

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Stellar Lifecycle

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Blackbody Spectrum

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Stellar Absorption Spectrum

Simulated absorption spectrum based on spectral type. Hover over lines to identify elements.

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Stellar Fusion

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15Stellar Notes

Spectroscopic Binary

About 14y orbital period; also RV 0.152360d suggesting possible light var. Spectra indicate triple system. Long period | SB, sep. 0.48", resolved by speckle interferometry at 4-meter Mayall telescope.

Spectral

Component B, K/H/m lines indicate A5/A9/F2 respectively.

Dynamical

0.005".

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