TSERASKY (OR CERASKY), VITOLD KARLOVICH

(b. Slutsk, Minsk gugberniya, Russia, 9 May 1849; d. Meshcherskoe, near Podolsk, Moscow oblast, U,S,S,R., 29 May 1925)

astronomy.

Tserasky’s father was a secondary school geography teacher. The discovery of Donati’s comet in 1858 awakened his interest in astronomy. In 1867 he entered Moscow University and while a second year student worked at the observatory as parttime calculator. Tserasky received a gold medal for a student work on the motion of Mars. After graduating he became a supernumerary assistant at the observatory. In 1874 he took part in an arduous expedition to Kyakhta, on the Chinese border, to observe the transit of Venus.

After returning to Moscow, Tserasky began systematic photographic study of the sun, but in 1877 he became deeply involved in instrumental astro photometry. Simultaneously with the Potsdam and Harvard observatories, he conducted pioneering work in precise stellar photometry. In 1878 he was designated astronomer–observer at the Moscow observatory. In 1883 he defended his master’s dissertation on the determination of the brightness of white stars. The astrophotometer of Zöllner led him to invent an instrument (the Zöllner-Tserasky photometer) that became the subject of his doctoral dissertation (1887).

At the end of the 1870’s Tserasky began teaching at the Higher School for Women, which were begun by a number of progressive professors– advocates of higher education for women, who did not have the right to study in universities during the tsarist period. From 1882 he was lecturer at the University of Moscow; in 1884 he became Privatdozent; and in 1889 he was elected professor of astronomy. His public lectures also were very successful.

In 1884 Tserasky married Lidia Petrovna Shelekhova, later known for her discoveries of more than 200 variable stars on the negatives of the Moscow Observatory. In 1890 Tserasky succeeded Bredikhin as director of the Moscow observatory, and from 1895–1903 he supervised the reconstruction of the observatory and the renovation of its equipment. In 1914 he was elected corresponding member of the St. Petersburg Academy of Sciences. After retiring in 1916 because of his health, he settled in Feodosiya, in the Crimea. In 1922 he moved to the home of his son, a physician, not far from Moscow, where he died three years later.

In addition to his numerous works in photometry, Tserasky made in 1895 the first experimental determination of the lower limit of the temperature of the sun (3,500°K.), by melting a number of refractory minerals at the focus of a concave mirror having a diameter and focal length both of one meter. (On the basis of these data Scheiner computed the temperature of the surface of the sun at 6,600°K., which approximates the correct value.) Following his discovery, at the end of the last century, of a few variable stars. Tserasky organized systematic astrophotographic studies using a wideangled, short-focus astrograph (the “equatorial camera “) built according to his design. From the resulting negatives L. P. Tseraskaya discovered more than 200 variable stars. In 1885 Tserasky discovered luminous (silver) clouds and with Belopolsky determined their altitude at 80 kilometers (actual value ~ 82 km.). Tserasky studied meteors and invented an original instrument for determining their angular velocity. In 1911 he published the results of his photometric comparison of the stellar magnitude of the sun with that of Venus and a number of bright stars; his value of the stellar magnitude of the sun (-26.50) has become an important weight in world summaries. To determine the degree of flattening of the sun’s sphere Tserasky devised an original heliometric objective and, for detailed study of sunspots, a specially constructed eyepiece. In 1908 he constructed a device that used solar energy to set off an electric bell on his desk.

An unpublished photometric catalog of 466 circumpolar stars, found among Tserasky’s papers, was edited by G. A. Manova and was included in a collection of his selected works (1953).

BIBLIOGRAPHY

1. Original Works. Tserasky’s 92 published writings include O prokhozhdenii Venery po disku Solntsa v 1874 g. ( “On the Transit of Venus Across the Disk of the Sun in 1874”: Moscow, 1875): “Ob opredelenii yarkosti belykh zvedh “( “On the Determination of the Brightness of White Stars”), in Uchenye zapiski Moskov skogo universiteta, Otd. fiz.-matem., no.4 (1882), 105–176, his master’s diss.; “Astronomichesky fotometr i ego prilozhenia” ( “The Astronomical photometer and Its Uses”), in Matematichesky sbornik, 13 (1886), 551–632, his doctoral thesis; “Sur les nuages lumineux,” lumineux, in Annales de I’Observatoire astronomique de Moscou, 2nd ser., 2 , bks. 1–2 (1890), 177–180; “Études photométriques sur I’amas stellaire × Persei,” ibid., 3 bk. 2 (1896), 1–24; “Sur la température du soleil,” ibid., 121–122. also in J. Scheiner, strahlung und Temperatur der Sonne (Leipzig, 1899): “Ob opredelenii formy solnechnogo diska “( “On the Determination of the Form of the Solar Disk”), in Izvestia Akademii nauk, 11 , no. 2 (Sept. 1899), 59–60: “Études photométriques sur I’amas stellaire Coma Berenices,” in Annales de I’Observatoire astronomique de Moscou, 2nd ser., 4 (1902), 87–120, and 6 (1917), 33–44; “Détermination photométrique de la grandeur stellaire du soleil, “in Astronomische Nachrichten, 170 (1905), 135–138; “Surune équation personnelle dans les observations photométriques,” ibid., 171 (1906), 135–136; Sfericheskaya astronomia. Lektsii, chitannye v 1909–1910 gg. ( “Spherical Astronomy. Lectures Given in 1909–1910”; Moscow, 1910); “Détermination photométrique da la grandeur stellaire de soleil,” in Annales de I’Observatoire astronomique de Moscou, 2nd ser., 5 (1911), 1–30; “Un oculaire pour I’étude détaillée des taches solaires,” ibid., 31–33; “Un objectif héliométrique pour la détermination de la forme du disque solaire, “ibid., 34–35; “Détermination des erreurs constantes des observations photométriques,” ibid., 6 (1917), 45–61; and izbrannye raboty po astronomii ( “Selected Works on Astronomy”; Moscow, 1953).

II. Secondary Literature. On Tserasky and his work, see S. Blazhko, “W. Ceraski,” in Astronomische Nachrichten, 225 (1925), 111–112; “Nauchnye raboty professora V. K. Tseraskogo” ( “The Scientific Works . . .”), in Russky astronomichesky kalendar for 1925, 128–134; and “Vitold Karlovich Tserasky. Zhizneopisnie” ( “. . . A Description of His Life”), in Tseraskly’s Izbrannye raboty po astronomii ( “Selected Works on Astronomy,” V. V. Podobed, ed., Moscow, 1953), 11–29; 1. A. Kazansky’s bibliography of Tserasky’s works, ibid., 46–52; Y. G. Perel, “K voprosu o mirovozzrenii V. K. Tseraskogo” ( “Toward the Question of Tserasky’s World Views”), in Istoriko-astronomicheskie issle dovaniya (1955), no. 1, 323–334; and “Vitold Karolovich Tserasky,” in Vydayuschiesya russkie astronomy ( “Outstanding Russian Astronomers “; Moscow, 1951), 63–84; K. D. Pokrovsky, ”V. K. Tserasky, “in Russky astronomichesky Kalender for 1925, 115–127, published for his seventy–fifth birthday; B. A. Vorontsov–Velyaminov, “Nauchnaya deyatelnost V. K. Tseraskogo” ( “The Scientific Activity of V. K. Tserasky”), in Tserasky’s Izbrannye raboty po astronomii, 30–45; and F. Y. Zotov, “Vospominania o V. K. Tseraskom “( “Recollections. . .”), in Istoriko-astronomicheskie issledovaniya (1955), no. 1, 335–342.

P. G. Kulikovsky