The observatory, originally Observatorium astronomicum, Specula astronomica ad Sanctum Clementem Pragae Veteris, (Prager) Kőnigliche Sternwarte and then k.k. Sternwarte in Prag or Prager Sternwarte, owes its existence to the support of the Jesuit order and especially to Josef Stepling, its first director, who worked here until 1777, in the latter period under the title of Astronomus Regius. He saw to it that the Prague Clementinum Astronomical Tower was rebuilt as an observatory that was well equipped for its day and permitted systematic activity.
After the Jesuit order was abolished in 1773, the observatory was associated very closely as a royal institution with the university because it was usually directed by a university professor, though in its research work it was quite independent. One hundred years later, after the division of the university into Czech and German sections, it came under German tutelage, but with the establishment of the new Czechoslovak state it was made an independent state institution in 1920.
At this time the observatory also acquired an improved working capacity thanks to its relatively modern instrumentation and increased staffing. Although there had been problems with the unsuitable location in the Prague basin since the early nineteenth century, it was not until 1920 that observations could be moved outside the city, when Josef Jan Frič donated his private observatory at Ondřejov (about 40 km from Prague) which he had built for himself in 1898.
As the State Observatory of the Czechoslovak Republic (under the German occupation during World War II it was the Prague Observatory) it existed up to 1950 when it formed the basis for the Central Astronomical Institute, and after the establishment of the CSAS the observatory came under the authority of this body.
At the outset, the only people to work here were the director, his adjunct, a clockmaker and a servant and these were later joined by ancillary staff, in the latter third of the nineteenth century, these being two assistants. The aims of the observatory work mostly derived from its director. Under Antonín Strnad, first an adjunct and later director (1781-1799), in addition to astronomical observations (solar and lunar eclipses, occultation of fixed stars by the moon and so forth) he also performed meteorological observations which at that time were among the routine jobs at any observatory. Hence this was the start of an almost uninterrupted flow of basic data on the weather: the data preserved since 1775 represents one of the longest continuous collections of information in existence anywhere and a most valuable comparative resource on which the daily forecasts published even nowadays are based.
Under Martin Alois David, Strnad's successor, the nearest celestial objects were observed but attention was primarily focused on determining the geographical position of a number of localities in Bohemia. Another director, Karel Kreil, also supported geomagnetic observations as well as the meteorological ones, but astronomical observations receded into the background and it was not until the establishment of the Czechoslovak state that these were successfully revived and extended. State observatory staff studied the solar atmosphere, engaged in positional and meteoric astronomy, carried out research into variable stars and drew up statistics on the fixed stars; there was also some theoretical astronomy.
Reporting of the exact time to the city, which had been one of the observatory's tasks since the 19 th century (noon was indicated from the tower by flag-waving, which was later "confirmed" by the shooting of a cannon from Prague castle) was taken over at the end of the 1920s by the nationwide radio time-reporting service.
Observatory staff first published the results of their scientific work in RBLS prints and in Austrian and German astronomical yearbooks. From 1841, K. Kreil started publishing Magnetische und meteorologische Beobachtungen an der k. k. Sternwarte zu Prag, also in the 1840s there were four volumes of the Astronomisch meteorologische Jahrbuch für Prag and from 1866 Weinek published Astronomische Beobachtungen an der k.k. Sternwarte zur Prag. From 1921, an astronomical yearbook was published to which were added Publications of the Prague State Observatory. 1947 saw the start of publication of the Bulletin of the Astronomical Institute of Czechoslovakia, founded by the last of the State Observatory directors, Otto Seydl, which the CSA Sbasically continued to publish ever since.
Written by Hana Barvikova
American-Czech relations
Foreign exhibitions - invitations, programmes (1884): International Electrical Exhibition, Philadeplphia (1884). Sign.74, ser. no. 202, b. 38.
Participation of the observatory in foreign exhibitions, 1929: Request: American Museum of Natural History, New York for a photograph of the Great Meteor for the Memorial Hall and reply (1929). Sign.74, ser. no. 204, b. 38.
Correspondence with foreign scientists: M. W. Bruce (1896-98), C. W. Bruce (1897), W. W. Campbell (1891 - 1912), G. E. Hale (1904), A. M. Harding (1935), E. S. Holden (1890 - 1897), Keeler (1899), S. P. Langley (1890), E. Loomis (1873 - 1874), C. A. F. Peters (1875 - 1880), W. H. Pickering (1910), H. D. Schwartz (1937), J. Tatlock (1889), F. L. O. Wadsworth (1901), J. H. Wayman (1924), M. W. Whitney (1901), G. W. Zwack (1900). Sign. 75, ser. no. 205, b. 39-42.
Correspondence with foreign institutes - joint international events, requests for collaboration involving astronomy and meteorology, 1885 - 1913: University of the State of Missouri, Columbia (1901), Department of Commerce and Labor, Coast and Geodetic Survey, Washington (1910), U. S. Naval Observatory, Washington (1885 - 1913), Treasury Department, Office of the Coast and Geodetic Survey, Washington (1902). Sign.76, ser. no. 207, b. 43.
Correspondence with foreign institutes after 1918 (1923 - 1939): Lick Observatory University of California (1923), Adler Planetarium and Astronomical Museum, Chicago (1934), California Institute of Technology, Pasadena (1935), Department of Commerce, Coast and Geodetic Survey, Washington (1937 - 1939). Sign.76, ser. no. 208, b. 43.
Correspondence with foreign institutes - circulars and forms, often with requests for collaboration over scientific matters, 1885 - 1948: Frank P. Brackett Observatory, Science Observer, Boston (1885), Harvard College Observatory, Cambridge (1890, 1903, 1908), Pomona College, Claremont (1947), University of Chicago, Yerkes Observatory (1936), California Academy of Sciencies, San Francisco (1916), pacific Astronomical Society, San Francisco (1891), International Association of Terrestrial Magnetism and Electricity, Washington (1905,1948), Library of congress, Washington (1903), Smithsonian Institution, Washington (1883 - 1893), U.S. Department of Agriculture, Washington (1904), Coast and Geodetic Survey, Washington (1890). Sign. 76, ser. no. 209, b. 44.
Foreign institutes to 1918 - anniversaries of institutes, changes of directors, changes of name, reorganization, statutes, establishment of new institutes, 1878 - 1908: Smithsonian Institution, Washington (1878, 1887, 1907), American Academy of Arts and Sciences, Boston (1880), American Philosophical Society, Philadelphia (1892), American Academy of Arts and Sciences, Boston (1905), University of Chicago, Yerkes Observatory (1897), University of Missouri, Columbia (1901), Department of Research in Terrestrial Magnetism, carnegie Institution of Washington (1907). Sign.77, ser. no. 210, b. 44.
Foreign institutes after 1918: Department of the Interior, Victoria (1924), Griffith Observatory, Los Angeles (1935). Sign.77, ser. no. 211, b. 44.