ELODIE

ELODIE
Name	ELODIE
Caption	ELODIE spectrograph
Operator	Observatoire de Haute-Provence
Location	Haute-Provence Observatory
Altitude	650 m
Established	1993
Decommissioned	2006
Wavelength	Optical
Resolution	R ≈ 42,000

ELODIE.

Overview

ELODIE was a fiber-fed, cross-dispersed echelle spectrograph installed at the Observatoire de Haute-Provence on the Plateau de Valensole near Aix-en-Provence and operated by teams from the Centre National de la Recherche Scientifique, the CNRS-affiliated laboratories, and personnel from the Université de Provence. The instrument served programs associated with facilities such as the 1.93 m telescope (Observatoire de Haute-Provence), collaborations with groups at the Institut d'Astrophysique de Paris, and survey projects linked to the European Southern Observatory and the Max Planck Institut für Astronomie. Commissioned in the early 1990s, ELODIE played a central role in campaigns contemporaneous with projects like the Keck Observatory radial-velocity efforts, the Anglo-Australian Planet Search, and the California Planet Survey until its replacement by successors from consortia including the Observatoire de Genève.

Design and Specifications

ELODIE employed a white-pupil, cross-dispersed echelle layout with a fiber link from the Cassegrain focus of the 1.93 m telescope (Observatoire de Haute-Provence) to the spectrograph housed in a thermally controlled room adjacent to the telescope pier. The optical train incorporated elements comparable to designs used at the CFHT and the European Southern Observatory instruments, featuring an R ≈ 42,000 resolving power across approximately 390–680 nm and a simultaneous thorium-argon reference similar to calibrators used at the Harvard-Smithsonian Center for Astrophysics and the Geneva Observatory. The detector was a CCD array with performance characteristics analogous to devices installed at the W. M. Keck Observatory, with pixel scales and sampling often compared in papers alongside instrumentation at the Anglo-Australian Telescope and the La Silla Observatory.

Observational Programs and Discoveries

ELODIE's observing campaigns included radial-velocity surveys led by teams connected to the Observatoire de Genève, the Harvard-Smithsonian Center for Astrophysics, and the Institut d'Astrophysique de Paris, producing results contemporaneous with detections reported from the Lick Observatory and the Palomar Observatory. The instrument is noted for delivering the discovery data for exoplanet detections attributed in literature alongside findings from the ESO 3.6 m Telescope and the Subaru Telescope, influencing follow-up studies performed with the Hubble Space Telescope and the Spitzer Space Telescope. ELODIE observations contributed to characterization studies that referenced catalogs maintained by the SIMBAD database, the Hipparcos Catalogue, and the Two Micron All Sky Survey, with target lists overlapping those from the Geneva Extrasolar Planet Search and the California and Carnegie Planet Search.

Data Reduction and Software

Data reduction pipelines for ELODIE were developed by teams at the Observatoire de Haute-Provence and incorporated algorithms discussed in conference proceedings presented at meetings held by the International Astronomical Union, the European Astronomical Society, and workshops hosted by the SPIE community. The software performed order extraction, blaze correction, wavelength calibration against Th–Ar lamp spectra, and radial-velocity computation using cross-correlation masks akin to methods used at the Harvard-Smithsonian Center for Astrophysics and the Geneva Observatory. Reduced products were archived in formats interoperable with tools maintained by the Centre de Données astronomiques de Strasbourg and interfaces compatible with analysis packages from the Astropy Project and community codes circulated at NASA centers and the European Space Agency.

Calibration and Performance

ELODIE achieved long-term radial-velocity stability through simultaneous reference calibration and environmental control comparable to stabilization strategies employed at the European Southern Observatory and the Keck Observatory. Precision routinely reached a few tens of meters per second, with best-case performance cited in studies alongside instruments like HIRES and HARPS, enabling detection of short-period companions discussed in literature from the Royal Astronomical Society and the American Astronomical Society. Performance assessments were reported in journals such as those published by the Astronomical Society of the Pacific and the Astronomy & Astrophysics community, with follow-up comparison metrics used by teams at the Observatoire de Genève and the Institut d'Astrophysique de Paris.

Legacy and Influence on Modern Instruments

ELODIE influenced next-generation spectrographs including designs at the Observatoire de Haute-Provence replacement projects, instruments at the ESO, and high-precision programs developed by the Geneva Observatory and the Max Planck Institut für Astronomie. Its techniques for fiber feeding, simultaneous calibration, and pipeline automation were referenced in proposals for HARPS and in engineering reports circulated among groups at the European Southern Observatory, the Anglo-Australian Observatory, and the W. M. Keck Observatory. The archive and methodological legacy informed survey strategies adopted by teams affiliated with the NASA Exoplanet Science Institute, the SIMBAD database, and community software efforts such as the Astropy Project.

Category:Spectrographs Category:Observatoire de Haute-Provence