Circulars Volume 1-50

Circulars Volume 1-50

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This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1900 edition. Excerpt: ...The best of these seems to be stopping the driving clock for a few seconds every hour. By the above plan we hope to secure a complete list of all variable stars of short period brighter than the ninth magnitude at maximum whose variation exceeds half H magnitude and whose period is less than a day. Doubtless, many other variable stars of longer period, and stars of the Algol type may also be incidentally found EDWARD C. PICKERING. May 21, 1898. CIRCULAR No. 30. THE SUPPOSED VARIABLE STAR, Y AQUILAE. Measures to determine the light curves of variable stars of short period, north of declination--40, are now in progress with the meridian photometer. Four sets of four settings each are ordinarily made when the star to be observed is about half an hour east of the meridian, and again about an hour later. These measures are repeated on twenty or thirty nights. The principal error is that due to the unequal transparency of the air in different portions of the sky, the stars compared being often far apart. The accidental errors of measurement are small owing to the number of settings. Smooth light curves have been found for all the stars thus measured, with the exception of +10 3787. The designation Y Aquilae was given to this star by Mr. S. C. Chandler, and in his catalogue of variable stars he states that it varies from magnitude 5.3 to 5.7 in a period of 4.986 days. Also, that it was " Susp. by Gould, confirmed by Chandler, 1894; also by Yendell." It will be noticed that the period is so nearly five days, that for several months the same phase will recur at about the same hour angle, thus permitting errors to occur in visual observations by Argelander's-method, such as are mentioned in Circular No. 23, and which led to such wholly...
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Product details

  • Paperback | 40 pages
  • 189 x 246 x 2mm | 91g
  • United States
  • English
  • black & white illustrations
  • 1236954505
  • 9781236954503