Astrometric Accuracy on Tautenburg Schmidt Plates
Using a big Schmidt telescope for astrometric purposes we take advantage of a coma free field with sharp images of all objects up to the 20th magnitude. The main disadvantage of a Schmidt telescope is in its relatively short focal length and the necessary bending of the photographic plate during exposition. It is reduced to a minimum in the case of the Tautenburg Schmidt telescope (134/200/401). We have a focal length comparable to that of astrometric astrographs (the scale is 51″/mm) and a relatively slight bending of the 24 x 24 cm plate covering a 3.°1 x 3.°1 field. On the other hand this is a relatively small field for a wide–field telescope so that a sky survey becomes too expensive, and the scale also gives no opportunity of defining highly accurate relative proper motions (p. m.), e. g. internal p. m. of stars in clusters, as is the aim of long focus astrographs. Therefore, we should concentrate on the determination both of positions of faint objects, e. g. extragalactic radio sources and of absolute p. m. of stars with respect to a great number of galaxies in selected areas, making in this way a contribution to the approximation of an inertial system.
KeywordsProper Motion Photographic Plate Plate Centre Reference Star Extragalactic Radio Source
Unable to display preview. Download preview PDF.
- Klemola, A. R., Vasilevskis, S., Shane, C. D. and Wirtanen, C. A.: 1971, Publ. Lick Observ., vol. 22, part 2Google Scholar
- Schilbach, E.: 1984, Untersuchung der Eigenbewegungen von Sternen durch Anschluß an ferne Galaxien auf Platten des Tautenburger 2m Schmidt—Teleskops, Dissertation, Potsdam, unpublished.Google Scholar
- Schilbach, E.: 1987, Tartu Astrof. Obs. Publ., in press.Google Scholar
- Scholz, R.-D. and Rybka, S. P.: 1988, Astron. Nachr., in preparation.Google Scholar
- Yatsenko, A. I., Rybka, S. P. and Scholz, R.—D.: 1987b, Astron. Nachr. 308, No. 5, in press.Google Scholar