When is the best time to observe Prima Hyadum?

Prima Hyadum is best observed from October through December, with peak visibility during November when it transits around midnight in the Northern Hemisphere.

Where is Prima Hyadum located in the sky?

Prima Hyadum lies in the constellation Taurus at right ascension 04h 20m and declination +15° 38′.

What telescope do I need to see Prima Hyadum?

At magnitude 3.6, Prima Hyadum is visible to the naked eye from dark skies, easy in any binoculars.

Prima Hyadum — Star in Taurus

HIP 20205; Gamma Tauri; 54 Tauri

Magnitude 3.6^m Star Taurus (Tau) Visible

Star Map + List + Plan

About Prima Hyadum

Description

Prima Hyadum, Gamma Tauri, is a G-type giant of spectral class G9.5 IIIab about 161 light-years away — another prominent member of the Hyades open cluster. At magnitude 3.65 it marks the southwestern point of the V-shaped asterism. The star is about 13 solar radii with a luminosity of 85 Suns.

Observing Tips

Prima Hyadum is one of the V's brightest stars, easily spotted as one of the defining points of the Hyades asterism. Any binocular sweep of the Taurus V reveals it and its many cluster-mate companions as a loose gathering of warm-colored stars. Best observed November through March.

History

The name is Latin for "First of the Hyades," a medieval astronomical label given because of its position as the first (most westerly) of the V's bright stars to rise. The paired designation Secunda Hyadum (Delta1 Tau) marks the second star. Both names were formally adopted by the IAU in 2017.

Fun Facts

The Hyades open cluster contains hundreds of stars of all spectral types, making it the best testing ground for cluster-based calibrations of everything from stellar ages to exoplanet occurrence rates. Prima Hyadum itself serves as one of the cluster's anchoring bright giants — a K-type red clump star actively fusing helium in its core.