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SOPHIE Spectrograph

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First Light !

Installation of the spectrograph at the telescope in its thermally controlled chamber began on July 10 and was mostly complete by July 27. The four optical fibers were connected to the Cassegrain adapter on July 20, when the first measurements of actual fiber train throughput were made.

The instrument in its thermally-controlled chamber. The four sheaths containing the optical fibers can be seen coming into the chamber at the top. The metal box in the upper left contains the scramblers for the high-resolution fiber set. The four fibers coming of the box out can be clearly seen. The dewar holding the EEV 44-82 CCD (4102x2048 pixels) has an autonomy of 48 hours. The constant-pressure vessel, seen in the background, had not yet been sealed. The entire spectrograph is mounted on shock absorbers and is directly supported by the telescope pier structure. The instrument cover assembly has yet to be installed.

A detailed alignment procedure started soon thereafter when the final settings of the optical train were made, including grating and CCD fine positioning. This led to the first spectrum of a star (51 Peg, of course !) on the night of 31 July-1 August.

One extracted spectral order of the 51 Peg spectrum

By the end of the week (August 6) most of the essential hardware and software had been tested in its different configurations, including automatic reduction and order extraction.

For the two configurations (high-efficiency or HE and high-resolution or HR), the two fibers have approximately the same throughput. In order to achieve a higher spectral resolution the HR fibers have a 40 micron exit slit, and their throughtput is consequently a factor of 2.5 smaller, including the effects due to the optical scramblers.

The second part of the commissioning phase will take place on August 21-28, when the wavelength calibration, automated cross-correlation and order merging software will be tested and other components upgraded.

More details will be available in this page as soon as they become available.

08.08.06/rev. 09.08.06