When is the best time to observe Yed Prior?

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

Where is Yed Prior located in the sky?

Yed Prior lies in the constellation Ophiuchus at right ascension 16h 14m and declination -03° 42′.

What telescope do I need to see Yed Prior?

At magnitude 2.7, Yed Prior is visible to the naked eye from dark skies, easy in any binoculars.

Yed Prior — Star in Ophiuchus

HIP 79593; Delta Ophiuchi; 1 Ophiuchi

Magnitude 2.7^m Star Ophiuchus (Oph) Visible

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About Yed Prior

Description

Yed Prior is a red giant of spectral type M0.5III at magnitude 2.74 in Ophiuchus. Located about 171 light-years from Earth, it has a luminosity of roughly 630 times solar. It forms a close visual pair with Epsilon Oph (Yed Posterior) — the 'Yed' pair represents the hand of the Serpent Bearer.

Observing Tips

Yed Prior and Yed Posterior form a distinctive naked-eye pair in the western part of Ophiuchus, representing the hand grasping the Serpent. The two are separated by about 4.5 degrees. Yed Prior's orange-red color contrasts with the yellower Yed Posterior. Best observed June through September.

History

The name Yed Prior comes from Arabic 'yad' meaning 'the hand,' with Latin 'prior' meaning 'the first/preceding one' (it rises before Yed Posterior). The pair represents Ophiuchus's hand grasping the head of Serpens.

Fun Facts

The Yed pair (Delta and Epsilon Oph) is one of the easiest naked-eye star pairs to spot, separated by about the width of three fingers at arm's length. Despite appearing close, they are at quite different distances — about 171 and 108 light-years respectively.