Issue |
Astron. Astrophys. Suppl. Ser.
Volume 119, Number 2, October II 1996
|
|
---|---|---|
Page(s) | 373 - 390 | |
DOI | https://doi.org/10.1051/aas:1996251 | |
Published online | 15 October 1996 |
ELODIE: A spectrograph for accurate radial velocity measurements
1
Observatoire de Marseille, 2 Place Le Verrier, F–13248 Marseille, France
2
Observatoire de Genève, CH–1290 Sauverny, Switzerland
3
Observatoire de Haute–Provence, F–04870 Saint Michel l'Observatoire, France
Send offprint request to: D. Queloz
Received:
28
September
1995
Accepted:
15
February
1996
The fibre–fed echelle spectrograph of Observatoire de
Haute–Provence, ELODIE, is presented. This instrument has been
in operation since the end of 1993 on the 1.93 m telescope.
ELODIE is designed as an updated version of the
cross–correlation spectrometer CORAVEL, to perform very
accurate radial velocity measurements such as needed in the
search, by Doppler shift, for brown–dwarfs or giant planets
orbiting around nearby stars. In one single exposure a spectrum
at a resolution of 42000 () ranging from
3906 Å to 6811 Å is recorded on a 1024×1024 CCD. This
performance is achieved by using a
echelle
grating and a combination of a prism and a grism as
cross–disperser. An automatic on–line data treatment reduces
all the ELODIE echelle spectra and computes cross–correlation
functions. The instrument design and the data reduction
algorithms are described in this paper. The efficiency and
accuracy of the instrument and its long term instrumental
stability allow us to measure radial velocities with an accuracy
better than 15-1 for stars up to 9th magnitude in less than 30
minutes exposure time. Observations of 16th magnitude stars are
also possible to measure velocities at about 1-1 accuracy. For
classic spectroscopic studies (
>100) 9th magnitude stars
can be observed in one hour exposure time.
Key words: instrumentation: spectrographs / methods: data analysis / techniques: spectroscopic / radial velocities
© European Southern Observatory (ESO), 1996