Stephanion Observatory

The 30-inch Cassegrain reflector of the Stephanion Observatory

The first observations at the Stephanion Observatory, in southern Peloponnese, were undertaken in March 1967 (seven years before the establishment of the Kryonerion Astronomical Observatory) with a guest 38-cm reflector and a UBV photometer that belonged to the Bergedorf Observatory of the University of Hamburg, Germany. Since then a large number of instruments have been hosted at the 800-m altitude observatory, which is located at = 22d49m45s, = +37d45m9s, including French telescopes, for monitoring satellites, and a 40-cm reflector from the Utrecht Observatory, Netherlands. The Observatory is established on a 4100 m2 plot, owned by Professor L.N. Mavridis, who has kindly granted it for use by the University of Thessaloniki staff. In June 1971, the 30-inch (76-cm) Cassegrain reflector of the University of Thessaloniki was installed at the Observatory. Until 1975 (when the 123-cm Cassegrain Coude reflector at Kryonerion became operational), this was the largest telescope in Greece.

The 30-inch reflector is mounted asymmetrically. Its focal ratio is f/3 for the primary hyperbolic mirror and f/13.5 for the Cassegrain focus. It was constructed by Astro Mechanics, USA, a firm that has long ago discontinued making astronomical instruments. The majority of observations are carried out with a Johnson dual channel photoelectric photometer with an offset guider unit mounted in the Cassegrain focus. It includes an RCA 1P21 and an RCA 7102 photo-multipliers, both of which are refrigerated by dry ice (-70?C). Key photometric observations of variable stars (flare stars, cefeid variables, RS CVns, etc) have been undertaken in co-operation with large ground or space instruments, yielding more than 100 publications in international journals in recent years. The international demand for co-operative and simultaneous observations at the Stephanion Observatory stems from the strict differential method used for obtaining absolute, above atmosphere, stellar magnitudes in the international UBV system. The error in the calibrated magnitudes obtained is usually better than 0.02 magnitudes.
Stephanion Observatory: View of mount Killini Sunset at the nearby small village of "Stephanion" The telescope (detail of the mounting)

[Photos: courtesy E. Harlaftis]

Last modified: Wed Jan 16 10:35:49 EET 2002