Page:Madras journal of literature and science 3rd series 1, July 1864.djvu/107

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Discovery of two new variable Stars
95

supplied by the Berlin Academical Charts, the southern halves of which fall entirely within their limits.

N. R. Pooson.

Madras Observatory,
December 1863.





On the discovery of Two new variable Stars, by N. R. Pogson, Esq., f. r. a. s., Government Astronomer.

THE search for new minor planets maintained during the past year with the Madras equatoreal, although not successful in its primary object, has nevertheless been the means of adding to the list of recognised variable stars, two interesting members hitherto unknown. Trusting that a brief account of these discoveries will not be out of place in the Madras Journal, the following particulars have been communicated.

The first, now known as U Scorpii, was detected on the 20th of May 1863, shining as a star of the ninth magnitude, in a spot in which no such object had been previously recorded, though most carefully watched in each successive May since 1854. Micrometrical measurements from an adjacent known star at once proved its fixity, and thereby suggested its probable variability. The following evening sufficed not only to confirm this impression, but also to show that the new variable was one of an extraordinary character, changing in brilliancy with a rapidity equalled only by one star of a similar nature, discovered by Mr. Hind, in the constellation Gemini, in December 1855. Eight days later, when last seen, U Scorpii had diminished to below the 12th magnitude, or less than one-seventeenth of its