Fixed star:  RUKBAT
Constellation:  Alpha (α) Sagittarius
Longitude 1900:  15CAP14 Longitude 2000:  16CAP38
Declination 1900:  -40.48' Declination 2000:  -40.37'
Right ascension:  19h 23m Latitude:  -18.22'
Spectral class:  B9 Magnitude:  4.1

The history of the star: Rukbat

 from p.357 of Star Names, Richard Hinckley Allen, 1889.
[A scanned copy can be viewed on this webpage]

RukbatAlpha (α) Sagittarius, Rukbat, is a star on the horse's knee or leg.

Although figured as alpha it is not the brightest star in the constellation, there are actually ten brighter stars in Sagittarius.

Rukbat is variously written Rucba, Rucbah, Rukbah, and Rucbar, from the 15th century Tartar astronomer Ulug Beg's Rukbat al Rami, the Archer's Knee; in some early books it is Al Rami, the Archer himself. The Standard Dictionary has Ruchbar ur Ranich.

The Euphratean Nibat Anu, already alluded to, may be for this, or for some other of the chief components of the constellation; perhaps for epsilon (ε Kaus Australis) if, in early days, that star was comparatively as bright as now.

This star, alpha, and the two betas were known as Al Suradain, the two Surad, desert birds differently described, — by some as "larger than sparrows" and variegated black and white (magpies?); by others as yellow and larger than doves. [p.357 under beta].

[Star Names, Their Lore and Meaning, Richard Hinckley Allen, 1889].

 

 

The astrological influences of the constellation Sagittarius

The following are Ptolemy's remarks: "The stars at the point of the arrow in Sagittarius have influence similar to that of Mars and the Moon: those on the bow, and at the grasp of the hand, act like Jupiter and Mars . . . those in the waist and in the back resemble Jupiter, and also Mercury moderately: those in the feet, Jupiter and Saturn." ... By the Kabalists Sagittarius is associated with the Hebrew letter Vau and the 6th Tarot Trump "The Lovers." [Robson*, p.60.]

The astrological influences of the constellation Sagittarius given by Manilius:

"As for the Archer, when the foremost portion of his cloak rises, he will give birth to hearts renowned in war and will conduct the conqueror, celebrating great triumphs in the sight of all, to his country's citadels. Such a one will build high walls (moenia from Latin murus) one moment and pull them down the next. But if Fortune favours them too generously with success, the mark of her envy is to be seen on their faces, for she works cruel havoc upon their features. So was it that a dread warrior* paid for his victories at the Trebia, Cannae, and the Lake, even before the hour of his retreat, with such disfigurement." [Translator's note: *Hanibal who lost an eye (Livy 22.2.11: Sagittarius is one-eyed; see p.103] [Manilius, Astronomica, 1st century AD, book 4, p.267]

"But they whose lot it is to be born under the Centaur of double form delight in yoking a team, in bringing a fiery horse to obey the pliant reins, in following herds which graze all over the grasslands, and in imposing a master on every kind of quadruped and taming them: they soften tigers, rid the lion of his fierceness, speak to the elephant and through speech adapt its huge bulk to human skills in a variety of displays. Indeed, in the stars of this constellation the human form is blended with a beast's and placed above it; wherefore it has lordship over beasts. And because it carries a shaft poised on drawn bow, it imparts strength to limb and keenness to the intellect, swiftness of movement, and an indefatigable spirit." [Manilius, Astronomica, 1st century AD, book 4, p.241.] 

References:

*[Fixed Stars and Constellations in Astrology, Vivian E. Robson, 1923].