When is the best time to observe Zeta Bootis?

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

Where is Zeta Bootis located in the sky?

Zeta Bootis lies in the constellation Boötes at right ascension 14h 41m and declination +13° 44′.

What telescope do I need to split Zeta Bootis?

Splitting Zeta Bootis requires an aperture of roughly 200 mm or larger — the components are separated by about 0.3″ at magnitudes near 4.4. Larger apertures and steady seeing help resolve the pair cleanly.

Zeta Bootis — Double Star in Boötes

HIP 71795; Zeta Bootis; 30 Bootis

Magnitude 4.4^m DoubleStar Boötes (Boo) Visible

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1Physical Properties

Magnitude 4.43

Spectral Type A2III giant

Star Color White (B-V 0.05)

Distance 362 ly

2Position & Identifiers

RA 14h 41m 08.9s

Dec +13° 43' 42.0"

Constellation Boötes (Boo)

HR 5478

HIP 71795

HD 129247

Bayer Zeta

Flamsteed 30 Boo

Double Cat 9343

SIMBAD Wikipedia

3How easy to spot?

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Equipment	Bortle 3	Bortle 4	Bortle 5
Naked eye Naked eye	Medium+	Medium	Medium
50 mm finder 50mm finder	Easy	Easy	Easy
150 mm telescope 150mm scope	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 Triple

Components 3 (triple)

Component IDs AB

Separation 0.3″

Companion Mag 4.5

Companion Sp A0V

Position Angle 240°

Star Colors A: White B: Blue-white

Discoverer STF1865

Notes

AB 4.52 A2III, 4.55 A2III, 123.44y, a = 0.595". Colors for combined HR 5477-5478. Combined mag. 3.78V. vsini 156k/s | for blended HR 5477-8.

Separation over time

Period: 125.2 y Eccentricity: 0.980 Now: 0.28", PA 332° + 0.23" in 5 years

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

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7

Size Comparison

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8

Compare Stars

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9

Spectral Classification

10

Hertzsprung-Russell Diagram

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

11

Stellar Lifecycle

12

Blackbody Spectrum

13

Stellar Absorption Spectrum

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

14

Stellar Fusion

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15Stellar Notes

Dynamical

0.012".

16

Light Travel Time Machine

17

Relativistic Travel

Nearby in the Sky

Other targets within a few degrees — pan your scope a little and keep exploring.

Visibility scores assume a 150 mm Newton at Bortle 4.

Pi Boo

HIP 71762; Pi Bootis; 29 Bootis

Easy

Easy double, sep 5.4″

Double Star mag 4.94 2.7° Boötes

Xi Boo

Easy

Easy double, sep 4.7″

Double Star mag 4.55 5.9° Boötes

NGC 5532

Medium

Bright spiral galaxy

Galaxy mag 12.0 6.6° Boötes

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