Andrew Cooper
Nov 23, 2023    Waikoloa, HI (map)
20cm f/6 Newtonian, Cave Astrola @ 76x
Seeing: 6 Transparency: 6 Moon: 0%

Brilliant white, no companion noted

Captain William Henry Smyth
Oct 19, 1830    No. 6 The Crescent, Bedford, England (map)
150mm f/17.6 refractor by Tully 1827

A coarse triple star, on the right foot of Pollux, in a rich field. A 3, brilliant white; B 13, and C 12, both pale plum colour; followed nearly on the parallel, Δ RA=40s, by a neat 9th-magnitude star. This object, with ξ on the other foot, is called Alhena, from al-hen'ah, a ring or brand on a horse's neck, and the two form the VIth Mansion of the Moon. These stars are also ξ Al-zerr, the button; and γ Al-meïsán, the proud marcher; and they are described by Kazwíní as two whitish glimmering stars in the Milky Way; but Tízíní makes the Alhena include also η, μ, and ν, in Castor's right foot; and some of his countrymen termed η and ν, Al-nuhhátï, the expressed dual of al-nuhháh, a large camel's hump, η is called Προπονς by Ptolemy, as being in the forefoot, but the name is best applied to H Geminorum, as the ante-foot, or star preceding the feet.

The alignment of this star is easy. A ray from Rigel through the middle star of Orion's belt, will pass clear of Betelgeuze to Alhena. The same imaginary line continued, passes close under Castor: it is also about two-thirds of the distance between Pollux and Betelgeuze.

Proper motions are detected in γ Geminorum, but not to the amount which was suspected, the most authentic values being:

  P....  RA +0".05  Dec. -0".08
  B....     +0".08       -0".02
 [Hipparcos +0".01381    -0".05496]

― A Cycle of Celestial Objects Vol II, The Bedford Catalogue, William Henry Smyth, 1844

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