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Elodie Spectrograph

This picture shows the spectrograph covered with its thermal insulation shroud. It is located in a temperature-controlled room in the second floor of the 1.93-m telescope building, one floor below the observing room and two floors below the telescope level. At the top of the picture is the (gold colored) cryostat holding the 1024x1024 SITe CCD detector. It is cooled with liquid nitrogen to keep the CCD at a constant temperature of -90 C to minimize dark noise. Filling the dewar is done automatically, through the tubing at upper right, twice a day: in late afternoon and early morning. The long black cylinder at the left is the exposure meter photomultiplier. The thick gray cables hanging down carry the electronic signals to and from the detector head. Another picture shows the detector assembly and the échelle grating without the thermal shroud.

One of the two pairs of 20-m long fiber optic cables carrying starlight from the Cassegrain focus adapter is visible below center left (orange cables), coming down from the ceiling (at left). The other pair arrives at the spectrograph optical assembly just below center (not visible in this picture).

The entire spectrograph is supported by a truss solidly attached to the the South telescope support pier, which isolates it from building and dome vibrations.