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PLANET NOTES FOR OCTOBER.

H. C. WILSON.

Mercury will be evening star during this month, coming to greatest eastern elongation, 23°44′ from the Sun, on Oct. 29. The planet may then be seen near southwestern horizon soon after sunset, but only for a short time.

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Venus is the bright star in the east, rising a little before three o'clock and reaching the meridian about nine o'clock in the morning. Her course is south

east ward through Leo. On the morning of Oct. 7 Venus will be in conjunction with the first magnitude star Regulus, the former being about one degree north of the latter. The waning moon will be in conjunction with Venus on the 19th.

Mars rises toward the northeast about midnight, and moves eastward through Cancer during this month. The planet is conspicuous for its ruddy color to the naked eye, being a little redder and brighter than the star Aldebaran. The Moon will be in conjunction with Mars on the night of October 16. The distance of Mars from the Earth is about 158,000,000 miles and the apparent diameter of the disk of the planet is only six seconds, so that observations of its surface-markings are yet very difficult.

Jupiter, Saturn and Uranus are evening stars but too low in the southwest for observation except during the twilight.

Neptune rises between nine and ten o'clock in the evening and may be observed under favorable conditions during the latter half of the night. The position of the planet October 1 is R.A. 5h 56m 38, Dec. 22° 13' 16", North.

Eros-The Astronomische Nachrichten No. 3662 contains an extension of the ephemeris of Eros, by Millosevich, from Jan. 1 to April 1, 1901.

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VARIABLE STARS.

J. A. PARKHURST.

Minima of the Variable Stars of the Algol Type.

(Given to the nearest hour in Greenwich Time.)

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The dates are taken as before from Dr. Hartwig's paper in the Vierteljahrsschrift, except for Y Cygni for which I have used Duner's data given in No. 3633

of the Nachrichten. These times are two and three hours later than those in Hartwig's ephemeris.

W Persei is called V Persei in Chandler's Third Catalogue.

SS CYGNI.-The maxima are now about a month behind the ephemeris, which is founded on the changes observed previous to the reversal of the order of maxima which occurred in the early part of 1900. The rise which was set for Aug. 8 by this ephemeris, did not take place till Sept. 7.

OBSERVATIONS OF VARIABLE STARS AT THE GERMAN
OBSERVATORIES.

The following items of news are extracted from Part 2 of Vol. 35 of the Vierteljahrsschrift, which has just appeared.

BAMBERG -For the year ending May 1, 1900, Dr. Hartwig reports 733 observations of variables by Argelander's method. Of this number 77 referred to SS Cygni. Of this star the intervals between the times of rise since Oct. 25, 1899, were 32, 35, 69 and 48 days. U Geminorum was found bright from April 1 to 3. Minima of Algol and A Tauri were observed on three nights, and light estimates were made of ß Lyrae, ŋ Aquilae and & Cephei on 18 nights. The variability of one of the Pleiades stars, B.D). + 24°531, was discovered by photography. Its magnitude in the B.D. is 9.5, but it was fainter than 12th magnitude in November 1899 and certainly fainter than 11th magnitude in April 1900.

HEIDELBERG.-Dr. Valentiner announces the early publication of Schönfield's original observations of variable stars. Most of them were made at Mannheim from 1865 to 1875. There are 35963 complete observatons of 117 variables, comprising over 80000 single estimates, besides 4000 or 5000 comparisons of the comparison stars among themselves. It is needless to say that the quality of these observations is fully equal to the quantity, and the publication will be simply invaluable.

MUNICH.-Observations of Nova Aurigae were continued and a decline of 0.2 magnitude was recorded in 1899. On the 22d of December it was estimated as 12.7 or 12 8 magnitude.

VIENNA - (The Von Kuffner Observatory.) Dr Wirtz has continued the investigation begun by Dr. Schwartzchild of the determination of the photographic light curves of variables. Preliminary reductions lead to the conclusion that the curve for 8 Cephei resembles that for 7 Aquilae, that is the photographic amplitude is nearly double the optical, thus showing a decided increase of redness at minimum.

OBSERVATIONS OF FAINT VARIABLES AT THE YERKES OBSERVATORY.

The greater part of the work hitherto done on variable stars consists in determinations of their maxima and periods, comparatively few of them being tol lowed through the complete cycle of their change. As a result our knowledge of the variation of most stars is fragmentary. For this reason the opportunity to observe taint minima with the Yerkes 12 and 40-inch telescopes was welcomed by the writer, and the following items from the work done between January and August, 1900, may be of interest. They are extracted from Bulletin No. 13 of the Yerkes Observatory:

This preliminary report will be followed by more definite results when the magnitudes of the comparison stars have been determined with the stellar photo

meter, now in use in this work. The magnitudes given in the present paper are only approximate, based on the assumption that the limit of the 12-inch is 14.0 magnitude, and that of the 40-inch 17.0 magnitude.

Of the 22 stars in this report, 16 are contained in Chandler's Third Catalogue of Variable Stars and supplements. For these stars Table I gives from this catalogue the minimum magnitude and number of minima on record, to show what was previously known on the subject; also the results of the work at the Yerkes Observatory from January to June 1900, giving the date and magnitude of the observed minima.

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Six of the stars in Table I did not pass minimum during the time covered by this report; the following notes show the observed magnitudes, the stars being referred to by their numbers only:

2625 14.5 magnitude by the end of January, brighter by middle of February. 2815 Carefully followed throughout its period. About 14 magnitude at normal light, but with considerable fluctuations.

2976 Has a 13 magnitude companion, 10".8 preceding, on the parallel.

5593 15 magnitude and rising early in February.

5831 Apparently stationary at 15 magnitude in February.

6871 About 15.5 magnitude early in June and still fading.

7458 Maximum 1899 October 1, at 7.5 magnitude; invisible in 40-inch (low power) 1900 July 20, therefore <17 magnitude: a range of nearly or quite 10 magnitudes.

Particular attention has been paid to new variables, not in the Third Catalogue, whose light-curves suggest very faint minima. Table II gives six stars selected from these, showing the number (in parenthesis, provisionally assigned by the writer), the place for 1900, found by micrometer measures with the 40inch, except for the 2d and 5th, the discoverer, and a reference to the announcement of discovery in the Astronomische Nachrichten.

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