Performance of the angle of arrival correction system of the I2T + ASSI stellar interferometer

¹ Observatoire de la Côte d'Azur, Fresnel Department, UMR 6528, Av. Copernic, 06130 Grasse, France
² ONERA, 29 Av. de la Div. Leclerc, BP. 72, 92322 Châtillon Cedex, France

Send offprint request to: S. Robbe

Received: 9 October 1996
Accepted: 23 December 1996

Abstract

The Active Sta bi li zation in Stellar Inter fero me try (ASSI) recombining table, developed at Office National d'Etudes et de Recherches Aérospatiales (ONERA), France, was implemented on the two-Telescope Interferometer (I2T) of the Observatoire de la Côte d'Azur (OCA) in 1993, compensating for the atmospheric turbulence wavefront fluctuations. Initial fringe observations were made in June 1994 with a 11 m North-South baseline. In this paper, we report the performance of the ASSI table servo system for correction of the angle of arrival. Tracking accuracy of about arcsec was achieved in typical seeing conditions ( cm) and on m_v=2 sources. Collected data allows to compare theoretical with observed temporal power spectra of the angle of arrival fluctuations, using Kolmogorov model. Spatio-temporal seeing parameters met during observations (Fried parameter r₀ and coherence time t₀) are estimated.