IAU Constellation (Boo) · Genitive: Boötis · Northern Sky

Boötes (The Herdsman) & Arcturus Guide

Boötes IAU constellation (907 sq deg, rank 13): June kite asterism anchored by Arcturus (−0.05), the brightest star of the northern celestial hemisphere.

Solid-Angle Area907 sq deg (Rank #13 of 88)
Best Evening MonthJune
Visibility Latitudes+90° to −50°
Brightest StarArcturus (Alpha Boötis) (−0.05)

Sky Navigation & Astrophysical Context

Spanning 907 square degrees of the northern spring and early-summer sky, Boötes is the thirteenth-largest constellation and one of the oldest figures recorded in Indo-European and Mediterranean sky lore. Its kite- or ice-cream-cone-shaped body rises north-northeast from its dazzling base star Arcturus (Alpha Boötis, V = −0.05), a K1.5 IIIpe red-orange giant at 11.26 parsecs that outshines every other star north of the celestial equator.

Generations of observers have located Boötes by following the curved arc of the Big Dipper's handle (Alioth, Mizar, Alkaid) 30° southeastward via the mnemonic 'Arc to Arcturus.' Above Arcturus, the shoulders and waist of the Herdsman are outlined by Nekkar (Beta Boötis), Seginus (Gamma Boötis), Princeps (Delta Boötis), Rho Boötis, and Izar (Epsilon Boötis), while Northern Boötes houses the radiant of the intense Quadrantid meteor shower each January 3–4.

For double-star observers, Boötes is legendary for Izar (Epsilon Boötis, dubbed 'Pulcherrima' or 'Most Beautiful' by Friedrich Georg Wilhelm von Struve), which pairs a +2.5-magnitude K0 II-III orange giant with a +4.8-magnitude A2 V blue-green main-sequence star separated by just 2.9 arcseconds, as well as the colorful yellow-and-purple visual binary Xi Boötis.

Bordering IAU Constellations: Canes Venatici, Ursa Major, Draco, Hercules, Corona Borealis, Serpens Caput, Virgo, Coma Berenices.

Equatorial Center Position & Transit Altitude

Boötes is centered near Right Ascension 14h 41m 24s, Declination +31° 12′ 00″ (The Herdsman).

J2000 Equatorial Sky Position (Boötes) +90° 0° −90° 24h 12h RA 0h Peak Meridian Altitude 81° 40°N Lat 29° 30°S Lat RA: 14h 41m 24s Dec: +31° 12′ 00″ Epoch: J2000.0 · 907 sq deg (Rank #13) First-party vector diagram derived from IAU / CDS SIMBAD / Gaia DR3 astrometry.

Practical Star-Hopping & Observing Tips

  • Follow the curve of the Big Dipper handle away from the bowl by ~30° to land directly on amber-gold Arcturus (V = −0.05).
  • Test a 100 mm+ telescope at 150×–200× on steady June nights to split Izar (Epsilon Boötis) into its orange primary and bluish secondary.
  • Use binoculars to split Mu Boötis (Alkalurops, 108 arcseconds) and Nu¹/Nu² Boötis near the border with Corona Borealis.

Notable Celestial Objects in & Near Boötes

Cataloged Stars and Deep-Sky Objects Associated with Boötes
ObjectFamilyClassificationRA (J2000)Dec (J2000)Min. Instrument
Arcturus (Alpha Bootis Red Giant)starsK-type red giant branch star (thick-disk / Arcturus stream)14h 15m 39.67s+19° 10′ 56.7″Naked eye
Mizar & Alcor (Zeta Ursae Majoris System)multiple-starsSextuple A-type stellar system (first telescopic & first spectroscopic binary)13h 23m 55.54s+54° 55′ 31.3″Naked eye for Mizar–Alcor; any 40–60 mm telescope at 40× for Mizar A–B
Messier 13 (Hercules Globular Cluster)globular-clustersGlobular cluster16h 41m 41.24s+36° 27′ 35.5″7×50 binoculars (naked eye under dark skies)

Scientific Sources Cited