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Astron. Astrophys. 358, L59-L62 (2000)


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Letter to the Editor

Optimizing Doppler estimates for extrasolar planet detection

I. A specific algorithm for shifted spectra

A. Chelli

Laboratoire d'Astrophysique, Observatoire de Grenoble, B.P. 53, 38041 Grenoble Cedex 9, France

Received 15 March 2000 / Accepted 8 May 2000

Abstract

We present an optimized algorithm to estimate from shifted stellar spectra the variations of radial velocity caused by a rotating planet. This algorithm is based on a rigorous approach in the spectral Fourier space that uses a weighted analysis of the cross spectrum phase between the high resolution spectra of the object and an appropriate reference. We give a simple method to calculate the best value of the stellar radial velocity in the presence of photon noise from a non linear least square fit, and we derive a formal expression for the velocity error. We show experimentally that the Fourier approach gives much better results than the classical cross-correlation technique.

Key words: methods: data analysis – techniques: spectroscopic

Send offprint requests to: Alain Chelli

© European Southern Observatory (ESO) 2000

Online publication: June 20, 2000

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