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Proceedings Paper

The exoplanet hunter HARPS: unequalled accuracy and perspectives toward 1 cm s-1 precision
Author(s): Christophe Lovis; Francesco Pepe; François Bouchy; Gaspare Lo Curto; Michel Mayor; Luca Pasquini; Didier Queloz; Gero Rupprecht; Stéphane Udry; Shay Zucker
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Paper Abstract

We present results from the first two years of operations of the HARPS spectrograph installed on the ESO 3.6m telescope at La Silla Observatory, Chile. This instrument, primarily built to detect extrasolar planetary systems, was designed to achieve the highest radial velocity precision ever, thanks to high mechanical and environmental stability, stable illumination, accurate wavelength calibration and tracking of instrumental drifts. HARPS has demonstrated a long-term accuracy at the 1 m s-1 level and below, exploring a new regime in RV precision. We present recent improvements in the wavelength calibration process, including the creation of a new ThAr reference atlas and the use of a much larger number of lines to fit the wavelength solution. We have also investigated the intrinsic stability of ThAr calibration lamps and show that they are able to provide a long-term wavelength reference at or below the 1 m s-1 level. Other instrumental error sources such as guiding accuracy and photon noise are discussed and a global error budget is presented. These efforts to further improve the RV precision are also part of a broader study to build a ultra-high accuracy spectrovelocimeter for the ESO OWL telescope, the CODEX project. The aim of this instrument is to reach an accuracy of 1 cm s-1 over timescales of at least ten years. This requires to push down the limits of present-day calibration techniques and to explore new technologies able to provide ultra-precise Doppler measurements.

Paper Details

Date Published: 28 June 2006
PDF: 9 pages
Proc. SPIE 6269, Ground-based and Airborne Instrumentation for Astronomy, 62690P (28 June 2006); doi: 10.1117/12.669991
Show Author Affiliations
Christophe Lovis, Observatoire de Genève (Switzerland)
Francesco Pepe, Observatoire de Genève (Switzerland)
François Bouchy, Observatoire de Haute-Provence (France)
Gaspare Lo Curto, European Southern Observatory Chile (Chile)
Michel Mayor, Observatoire de Genève (Switzerland)
Luca Pasquini, European Southern Observatory (Germany)
Didier Queloz, Observatoire de Genève (Switzerland)
Gero Rupprecht, European Southern Observatory (Germany)
Stéphane Udry, Observatoire de Genève (Switzerland)
Shay Zucker, Weizmann Institute of Science (Israel)

Published in SPIE Proceedings Vol. 6269:
Ground-based and Airborne Instrumentation for Astronomy
Ian S. McLean; Masanori Iye, Editor(s)

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