Page:The story of the comets.djvu/307

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Ephemeris of Halleys Comet.
249

On March 12 the comet will have nearly the same R.A. as d Piscium (5·0), and be only 2′ S. of that star.

On March 21 the comet will have nearly the same R.A. as Algenib (γ Pegasi) of mag. 3·0, and be 7¼º S. of that star.

After about April 1 it will be matter of some uncertainty how long it will be possible to see the comet as it approaches the Sun to make its perihelion appulse. It will certainly cease to be visible much longer in the evening, but will reappear in the morning early in May, still in the Northern hemisphere, and still in Pisces, where it will be till about May 14. After that its R.A. will rapidly increase, the Declination slowly diminishing till about June 1, when the comet will pass into the Southern hemisphere and remain there until it disappears altogether, which may be in June or July.

The comet will be nearest to the Earth (distance, 12 million miles) and therefore at its maximum brilliancy about May 18, but the Moon, "new" on May 8, will to some extent spoil the comet; and May 21 will afford us the best view, all things considered.

After quitting Pisces, about May 14, its path will be through Aries, Taurus, Gemini, the head of Orion, Canis Minor, Hydra, Sextans, the feet of Leo, and Virgo, where it will probably be last seen: but the long days and short nights, and full Moon on May 22, with no true night at all during many weeks, will seriously interfere with observations of the comet. During its post-perihelion career the comet will pass not far from a considerable number of bright stars which may be a little help to those who, living in the Southern hemisphere, at the Cape, or in Australia, or New Zealand, may desire to follow the comet as long as possible. Aldebaran (α Tauri, mag. 1·0), Betelgeuze (α Orionis, mag. 1·0), γ Geminorum (2·0), and Procyon (α Canis Minoris, mag. 0·5) are some of the stars to which the foregoing remark applies.

In the Ast. Nach., vol. clxxxi, No. 4330, June 12, 1809, Matkiewitsch of Pulkova gives an ephemeris differing only slightly throughout from the foregoing.