IAU Constellation (Her) · Genitive: Herculis · Northern Sky

Hercules Constellation Guide & Objects

Hercules IAU constellation guide: Keystone asterism navigation, area (1225 sq deg), best summer visibility, and deep-sky targets M13 and M92.

Solid-Angle Area1225 sq deg (Rank #5 of 88)
Best Evening MonthJuly
Visibility Latitudes+90° to −50°
Brightest StarKornephoros (Beta Herculis) (+2.77)

Sky Navigation & Astrophysical Context

Hercules is the fifth-largest of the 88 modern International Astronomical Union (IAU) constellations, covering 1,225 square degrees of the northern summer sky. Despite its immense footprint between Boötes and Lyra, Hercules contains no first- or second-magnitude stars; its brightest member is Beta Herculis (Kornephoros) at visual magnitude +2.77.

Visual observers navigate Hercules via the Keystone asterism—a prominent four-star trapezoid formed by Eta, Zeta, Pi, and Epsilon Herculis. The western edge of the Keystone between Eta and Zeta Herculis marks the exact star-hopping line to Messier 13, the premier globular cluster of the northern hemisphere, while the older and more compact Messier 92 lies in the northern reaches of the constellation.

Because Hercules transits near the zenith for mid-northern observers during June and July evenings, its targets pass through minimal atmospheric airmass, providing stable seeing conditions for high-magnification globular cluster resolution and double-star splitting.

Bordering IAU Constellations: Draco, Boötes, Corona Borealis, Serpens Caput, Ophiuchus, Aquila, Sagitta, Vulpecula, Lyra.

Equatorial Center Position & Transit Altitude

Hercules is centered near Right Ascension 17h 00m 00s, Declination +30° 00′ 00″ (Hercules (Hero of Roman/Greek Mythology)).

J2000 Equatorial Sky Position (Hercules) +90° 0° −90° 24h 12h RA 0h Peak Meridian Altitude 80° 40°N Lat 30° 30°S Lat RA: 17h 00m 00s Dec: +30° 00′ 00″ Epoch: J2000.0 · 1225 sq deg (Rank #5) First-party vector diagram derived from IAU / CDS SIMBAD / Gaia DR3 astrometry.

Practical Star-Hopping & Observing Tips

  • Locate the Keystone asterism two-thirds of the way along an imaginary line connecting Vega (in Lyra) and Arcturus (in Boötes).
  • Sweep 2.5° south of Eta Herculis along the western Keystone edge to center Messier 13 in binoculars or a finder scope.
  • Form an equilateral triangle north of Pi and Eta Herculis to locate Messier 92.

Notable Celestial Objects in & Near Hercules

Cataloged Stars and Deep-Sky Objects Associated with Hercules
ObjectFamilyClassificationRA (J2000)Dec (J2000)Min. Instrument
Messier 13 (Hercules Globular Cluster)globular-clustersGlobular cluster16h 41m 41.24s+36° 27′ 35.5″7×50 binoculars (naked eye under dark skies)
Messier 92 (NGC 6341 in Hercules)globular-clustersGlobular cluster17h 17m 07.40s+43° 08′ 09.4″7×50 binoculars
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
Hercules X-1 (HZ Herculis) — X-Ray Pulsarcompact-objectsAccreting X-Ray Pulsar Binary16h 57m 49.81s+35° 20′ 32.6″250–400 mm telescope visually; 150 mm+ CCD astrograph

Scientific Sources Cited

  • IAU Official Constellation Boundaries & Designations (IAU 88 Recognized Constellations): Delporte, E. 1930, Délimitation scientifique des constellations (IAU / Cambridge University Press) — International Astronomical Union (IAU)
  • SIMBAD Astronomical Database (CDS) (2026-10 release): Wenger, M., et al. 2000, A&AS, 143, 9 (The SIMBAD astronomical database) — Centre de Données astronomiques de Strasbourg
  • Revised New General Catalogue and Index Catalogue (RNGC/IC) (2024/2026 edition): Steinicke, W. 2010, Observing and Cataloguing Nebulae and Star Clusters (Cambridge Univ. Press); Verga, M. OpenNGC (CC-BY-SA 4.0 / data tables) — Wolfgang Steinicke / OpenNGC