dimanche 5 octobre 2008

Hydra 8

The Water-serpent's gleaming bend.
Brown's Aratos.
α, 2, orange.

Alphard, Alfard, and Alpherd, — Alphart in the Alfonsine Tables and Pherd with Hyde, — are from Al Fard al Shujāʽ, the Solitary One in the Serpent, well describing its position in the sky. Caesius gave Alpharad, which on the Reuter wall-map was Alphrad; and a still more changed title is Alphora. The Arabs also knew α as Al Faḳār al Shujāʽ, the Backbone of the Serpent; but Ulug Beg changed this to Al ʽUnk al Shujāʽ, the Serpent's Neck; and its shared the Suhel of other bright stars as Suhel al Fard, and Suhel al Shām, the Solitary, and the Northern, Suhail.
Tycho first called it Cor Hydrae, the Hydra's Heart, — Riccioli's Kalb Elhavich and Kalbelaphard, — which, with the alternative Collum Hydrae, the Hydra's Neck, is current even now.
In China it determined the 8th sieu, and was the prominent star of the Red Bird that combined the seven lunar divisions of the southern quarter of the heavens. Its longitude is said to have been ascertained there in the 19th century before our era, but the statement may be questionable; as also it was observed passing the meridian at sunset on the day of the vernal equinox during the time of the emperor Yao, about 2350 B.C. It culminates on the 26th of March.
β and ξ were the Chinese Tsing Kew, the Green Hill.
δ, ε, ζ, η, ρ, and σ, 3d to 5th magnitudes, on the head, were Ulug Beg's Min al Azʽal, Belonging to the Uninhabited Spot.
ε is a remarkable triple, — an 8th‑magnitude 3 1/2ʺ from a 3.8‑magnitude, the latter divided by Schiaparelli, in 1892, into two of nearly equal brightness 0ʺ.2 apart, — which probably form a rapid ternary system.
ι, a 4th‑magnitude, was the Chinese Ping Sing, a Tranquil Star.
κ, a 5th‑magnitude, and the stars of about the same brilliancy extending from it to β, with β Crateris, were Al Sufi's Al Sharāsīf, the Ribs.
σ, 4.6, was Ulug Beg's Al Minḣar al Shujāʽ, the Snake's Nose.
τ1, 4.9, flushed white, and τ2, lilac, with ι and the 5th‑magnitude A, form the curve in the neck, Ptolemy's Καμπή; but Kazwini knew them as ʽUḳdah, the Knot.

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