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Events
The SOPHIE echelle spectrograph, installed at the
1m93 telescope in Haute-Provence Observatory, is open
to the community since late October 2006. Interested astronomers are
invited to submit their observing proposals to INSU for next semester when the
next call for proposals will be open, normally in April and October each year.
After finishing the integration phase, the
installation of the spectrograph in the
telescope building took place in mid-July 2006, with
first
light happening shortly thereafter.
Three periods of commissioning (to be followed
later by several periods of scientific validation) took place in
August and September 2006. Results from the technical tests and the scientific
validation observations are
available.
The instrument is regularly open to proposals every semester. A
complete documentation package on the SOPHIE instrument is
available :
Characteristics
SOPHIE is installed in the old coudé room (which has been modified
accordingly) inside a thermally controlled chamber. The dispersing
elements (échelle grating and cross-dispersing prism) are placed
in a tank closed by the Schmidt plate. The tank is
filled with nitrogen gas and closed to be kept at constant pressure. See
design layout.
The CCD detector is an EEV 44-82 with 4102x2048 pixels of 15 microns,
thinned, back-illuminated and has an anti-reflection coating. It is kept
at a constant temperature of –100°C in a dewar with an autonomy of 48
hours. The controler used is a GenII from San Diego State University. The read-out
time is selectable between less than 30 sec in "fast mode" with a read-out
noise < 8e- and less than 3 min in "slow mode" with a read-out noise
< 4e-.
SOPHIE spectra cover the wavelength interval from 382 through 693 nm
in 39 orders with two different spectral resolutions:
- R=75000 (High resolution or HR mode)
- R=39000 (High efficiency or HE mode)
The calculated efficiency is 4% and 8% for the HR and HE modes
respectively, which implies a gain of 2.5 magnitudes with respect to ELODIE
in HE mode. The calculated S/N ratio indicates
than a S/N of 100 will be reached in 1 hour for V=10 in HR mode. The HE mode
reaches a magnitude fainter. The expected radial velocity accuracy is
expected to be near +/-2 m/s (HR mode with simultaneous Th). The results
obtained this Summer have allowed us to confirm these figures
(see : Performance
assesment for details).
Light is transported from the telescope to the spectrograph via a pair of
optical fibers each with a 3 arc-sec diameter aperture. Two fiber sets are
available (HE and HR). The fiber heads are housed in a special
adapter at the
Cassegrain focus, the same used for ELODIE.
A
slide show illustrates the different components of the
adapter (pictures taken on December 2003) also called "bonnette".
The adapter also houses the
calibration lamps (Continuum tungsten lamp, Thorium-Argon lamp) with an
associated attenuator, the refraction correctors and the CCD
autoguider, as well as a main
shutter. The HR fiber set includes a set of
optical scramblers to stabilize the output beam. Selection of either the HR set or
the HE set is be done through software. In each set one fiber is used from the
object and the other for the Thorium or the sky spectrum.
The software system for SOPHIE is made up of three different sub-systems: (1)
Observation preparation sub-system, or STS, (2) Spectrograph and camera control sub-system
and (3) Data reduction sub-system, or DRS. Data reduction is automatic and runs
asynchronously with the observation software. A fourth sub-system is used to
archive all files (raw, reduced and data products).
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