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Astron. Astrophys. Suppl. Ser. 136, 193-204

Autoguider locked on a fiber input for precision stellar radial velocities[*]

F. Bouchy - P. Connes

Send offprint request: F. Bouchy

Service d'Aéronomie du CNRS, BP. 3, F-91371 Verrières-le-Buisson Cedex, France

Received October 23; accepted December 7, 1998


Measurement of stellar radial velocities (RV) is one acknowledged approach for planetary-search and asteroseismology programs. We study the incomplete scrambling action of a fiber feeding a spectrograph, which leaves RV errors at a level of few m/s. Observations realised with the ELODIE fiber-fed crossed-dispersion spectrograph at the 193-cm telescope of Observatoire de Haute-Provence (OHP) are presented. A fiber-locked autoguider (called FLAG) has been specifically built to reduce the stellar-beam geometrical fluctuations within the spectrograph. With FLAG, the fiber-input plays the role of guiding detector. Automatic focusing is also accomplished by the system. The design and performance characteristics of the instrument tested at the 152-cm telescope of OHP are reviewed here.

Key words: atmospheric effects -- instrumentation: spectrographs -- techniques: radial velocities -- stars: oscillations -- planetary systems

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