When is the best time to observe Sigma Coronae Borealis?

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

Where is Sigma Coronae Borealis located in the sky?

Sigma Coronae Borealis lies in the constellation Corona Borealis at right ascension 16h 15m and declination +33° 52′.

What telescope do I need to split Sigma Coronae Borealis?

Splitting Sigma Coronae Borealis requires an aperture of roughly 80 mm or larger — the components are separated by about 7.4″ at magnitudes near 5.6. Larger apertures and steady seeing help resolve the pair cleanly.

Sigma Coronae Borealis — Double Star in Corona Borealis

HIP 79607; Sigma Coronae Borealis; 17 Coronae Borealis

Observable Double Star Excellent (69/100)

Sep: 7.4", Companion: mag 6.5

Magnitude 5.5–5.7^m DoubleStar Corona Borealis (CrB) Visible

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Observe

1Physical Properties

Magnitude 5.64

Range 5.54 - 5.69

Period 27.4 hours

Variable Type RS CVn (Chromospherically Active)

Spectral Type G0VCaIIe

Star Color Yellow (B-V 0.51)

Distance 72 ly

2Position & Identifiers

RA 16h 14m 40.8s

Dec +33° 51' 31.0"

Constellation Corona Borealis (CrB)

HR 6063

HIP 79607

HD 146362

Bayer Sigma

Flamsteed 17 CrB

Variable ID TZ CrB

Double Cat 9979

SIMBAD Wikipedia

3How easy to split?

Primary 5.6 mag Companion 6.5 mag Separation 7.4″

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Telescope	Bortle 3	Bortle 4	Bortle 5
80 mm refractor 80mm refr.	Easy	Easy	Easy
150 mm Newton 150mm Newt.	Easy	Easy	Easy
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)

5Light Curve

6Multiple Star System Quadruple D: optical

Components 4 (quadruple)

Component IDs AB

Separation 7.4″

Companion Mag 6.5

Companion Sp G1V

Position Angle 240°

Star Colors A: Yellow B: Yellow

Discoverer STF2032

Notes

AB 5.58 F8V, 6.59 G1V, 1000.0y, a = 6.599". Radio binary: component B is HR 6064. C, 13v at 9" and D, 10.8v at 71" | optical. Also, 12.5v at 633" CPM.

Separation over time

Period: 656.7 y Eccentricity: 0.771 Now: 7.4", PA 240° + 0.06" in 5 years

Apparent separation over time, computed from ORB6 orbital elements. Steep curves indicate fast-changing pairs — catch them while they're splittable.

Eyepiece View

Telescope Eyepiece

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80x Dawes: 1.9″ TFOV: 0.6°

Seeing

Scale Realistic = true angular size

A: 5.6 · B: 6.5 · Sep: 7.4″ · PA: 240° · N up, E right

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

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Size Comparison

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Spectral Classification

10

Hertzsprung-Russell Diagram

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Stellar Lifecycle

12

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

Variable Star

ADS 9979A, Delta Sct, amp. 0.05V, 1.139789d, with possible secondary period of 0.1d. ADS 9979D = NSV 7576, 10.8v | optical, suspected var. in 1868, not confirmed.

Spectroscopic Binary

ADS 9979A, mag. diff 0.2, one component the Delta Sct var. 1.1398d, K 60.1k/s, V0 -11.9k/s, msin3i 0.133, | asini 0.942. Both components vsini =<25k/s.

Dynamical

0.048".

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