POWALKY, KARL RUDOLPH

(b. Neudietendorf, near Gotha, Germany, 19 June 1817; d Washington, D.C., 11 July 1881)

astronomy.

The details of Powalky’s scientific education are unknown. He received his practical training as assistant, from 1842 to 1847, at the Hamburg observatory, then directed by K. L. C. R,ümker, whose student he later called himself. From 1850 to 1856 he was at the duke of Mecklenburg’s private observatory at Seeberg, near Gotha. where he had an important part in the computation of P. A. Hansen’s lunar and solar tables. In the summer of 1856 he moved to Berlin, where he won deserved acclaim with his calculations for the Berliner astronomisches Jahrbuch Powalky received his doctorate in 1864, at the age of forty-seven; his dissertation, submitted to the University of Kiel, was entitled “De transitu stellae Veneris ante discum solis anno 1769 peracto ad solis parallaxin accuratius determinandam.” In this work he derived a solar parallax between 8.832” and 8.86”, which agreed very closely with the value of 8.86”previously obtained by Foucault. This finding led to a controversy between Powalky and Le Verrier. Powalky left Berlin in 1873 for Washington, where he worked at the Bureau of the Census and at the Naval Observatory. He was, however, never able to find a post in the United States that fully matched his desires.

After taking part at Hamburg in observations of stellar occupations from 1845 to 1847, Powalky turned exclusively to theoretical work. He reduced Rümkers observations of Halley’s comet (1835III) and computed the elements of the comets 1846III (Brorsen), 1846V (Hind). 1846VIII, 1847V (Brorsen-Metcalf), and 1847VI. Later, at Berlin, he made corresponding calculations for the comets 1858VIII (Encke) and 1860III. It was through Powalky’s ephemerides that W. J. Foerster sighted Encke’s comet on 7 August 1858 at Berlin.

Also at Berlin, Powalky engaged in extensive theoretical research. In 1863 the Berliner astronomisches Jahrbuchpresented solar ephemerides computed on the basis of the sun charts of Hansen and Olufsen. Considering such data important for determining orbits of the minor planets, Powalky published corrections of the solar positions for 1845-1862. In particular he calculated the following ephemerides for the Berlin yearbook: the moon (using Hansen’s tables, 1863-1875), the sun (1871-1875), Saturn and Uranus (1860), Mercury to Uranus (1861), Mercury to Neptune (1862-1868), Jupiter to Neptune (1871-1872), Mars to Neptune (1873-1875), the satellites of Jupiter (1870, 1873-1875), Saturn’s rings (1868-1870, 1873-1875), eclipses (1871-1872), the transit of Venus (1874), star positions (employing J. P. Wolfer’s Tabulae reductionum, 1862-1868), and stellar occultations (1868-1876).

Especially interested in the minor planets, Powalky based his orbital computations on formulas taken from Hansen’s “Theorie der absoluten und speziellen Störungen der kleinen Pianeten” (1853-1859). Between 1856 and 1881 Powalky published computations of the orbital elements and ephemerides of eleven minor planets. In 1859 he identified a star missing in Bessel’s zone with the planetoid Amphitrite. For the Berliner astronomisches Jahrbuch he calculated the annual ephemerides of Juno (1860-1869, 1873) and computed those of Ceres (1873), Pallas (1873), Vesta (1868, 1873), and Astraea (1871, 1873). At various times between 1861 and 1883 he worked out the ephemerides for Fortuna (1860-1875), Harmonia(l860-1868, 1872, 1873), Nysa, Aglaia, Doris, and Pales (1861-1875), as well as those for thirty-two other minor planets. Even while in Washington, Powalky continued to contribute these computations to the Berliner astronomisches Jahrbuch until his death.

At Berlin, Powalky made a critical examination of the Greenwich observatory’s 1852 lunar observations and compared them with Hansen’s moon charts. He also published a reduction of the observations of the fixed stars made by Römker between 1826 and 1828 at Paramatta, Australia. In connection with his dissertation, he made several studies of phenomena pertaining to the transits of Venus and to the determination of solar parallax.

BIBLIOGRAPHY

I. Original Works. Powalky’s writings are listed in Generalregister der Astronomische Nachrichten, Bände 41 bis 80 (Kiel, 1938), 78-79; and … Bände 81 bis 120 (Kiel, 1891), 91; and in Poggendorff, III, 1063. Among them is “Neue Untersuchung des Venusdurchgangs von 1769 zur Bestimmung der Sonnenparallaxe,” in Schriften der Universität Kiel, 11 , no. 1 (1865). While in Washington he published “The Combination of the Different Results of Various Series of Observations,” in Monthly Notices of the Royal Astronomical Society, 34 (1874), 476-479; “Die Elemente der Sonnenbahn und die Massen der Planeten Venus und Mars,” in Astronomische Nachrichten, 88 (1876), 257-276; “Reduction von Lacaille’s AR-Bestimmungen sudlicher Sterne durch correspondierende Höhen (1751-1752),” idbi., 89 (1877), 183-190, 193-204; 90 (1877), 21-28; and “Comparison of the Observations of the Sun Made at Washington, 1866-1875, With Hansen’s Tables,7rdquo; in Monthly Notices of the Royal Astronomical Society, 41 (1881), 1–17.

II. Secondary Literature. A short biography is Gunther, “Karl Rudolf Powalky,” in Allgemeine deutsche Biographie, XXVI (1888), 494. An obituary is A. Hall, “Carl Rudolph Powalky,” in Astronomische Nachrichten, 100 (1881), 159.

Diedrich Wattenberg