When is the best time to observe Izar?

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

Where is Izar located in the sky?

Izar lies in the constellation Boötes at right ascension 14h 45m and declination +27° 04′.

What telescope do I need to split Izar?

Splitting Izar requires an aperture of roughly 100 mm or larger — the components are separated by about 2.8″ at magnitudes near 2.7. Larger apertures and steady seeing help resolve the pair cleanly.

Izar — Double Star in Boötes

HIP 72105; Epsilon Bootis; 36 Bootis

Observable Double Star Good (54/100)

Sep: 2.8", Companion: mag 4.8

Magnitude 2.7^m DoubleStar Boötes (Boo) Visible

Star Map + List + Plan

About Izar

Description

Izar (also called Pulcherrima) is one of the most beautiful double stars in the sky at magnitude 2.70 in Bootes. A telescope reveals a stunning pair — a golden-orange giant (K0II-III, mag 2.5) and a blue-white companion (A2V, mag 4.6) separated by about 2.9 arcseconds. Located about 203 light-years from Earth.

Observing Tips

Izar lies in the waist of Bootes, about 10 degrees northeast of Arcturus. Resolving the close pair requires a 4-inch or larger telescope at 150x or more. The color contrast — warm orange and cool blue — is exquisite. Best observed April through August when Bootes is well-placed.

History

The name Izar comes from the Arabic 'al-izar,' meaning 'the girdle' or 'veil.' The celebrated astronomer Friedrich Georg Wilhelm Struve gave it the Latin name Pulcherrima, meaning 'the most beautiful,' after resolving the pair and being struck by its color contrast.

Fun Facts

Struve's nickname 'Pulcherrima' (most beautiful) has stuck for nearly 200 years, and Izar regularly appears on lists of the finest double stars. Its tight separation makes it a good test of telescope optics and atmospheric seeing.

Observe

1Physical Properties

Magnitude 2.70

Spectral Type G9II-III bright giant

Star Color Orange (B-V 0.97)

Distance 202 ly

2Position & Identifiers

RA 14h 44m 59.2s

Dec +27° 04' 27.0"

Constellation Boötes (Boo)

HR 5506

HIP 72105

HD 129989

Bayer Epsilon

Flamsteed 36 Boo

Double Cat 9372

SIMBAD Wikipedia

3How easy to split?

Primary 2.7 mag Companion 4.8 mag Separation 2.8″

Telescope	Bortle 3	Bortle 4	Bortle 5
80 mm refractor 80mm refr.	Medium	Medium	Medium
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

Set a location in User Settings to see visibility data.

Best season Mar – May (peak: Apr)

5Multiple Star System Triple

Components 3 (triple)

Component IDs AB

Separation 2.8″

Companion Mag 4.8

Position Angle 347°

Star Colors A: Orange B: Orange

Discoverer STF1877

Notes

Binary with HR 5505. Colors for combined light. Mag. of blend, 2.37V.

Separation over time

Measured 1822 → 2023 (201 y)

Separation drift 2.7" → 2.8" (+0.10")

Rate +0.0005" / y

PA drift 318° → 347° (+29°, +0.144°/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.