Technical description:
Here, the cover of MegaPrime has been lifted up, and is still visible at the top of the picture. The two vertical boxes, the front one labeled MegaCam, are the two controllers of the camera. Each of them is processing the signals coming from half the CCDs of the mosaic. 
The data are sent by fiber optics directly to a PC-like computer located close to the observing room. The CCD mosaic is inside the cryostat, the blue flat cylinder that can be seen under the controller boxes. The braided hose leads to a vacuum pump: this picture was taken while MegaCam was being prepared for its first ride on the telescope. 
The small black cylinder seen just under the cover is the motor of the rotating valve, which sends pressure waves in the pulse tube used to cool the mosaic. The helium lines are the two bigger black hoses just under the motor. 
Glycol runs to many places, cooling all the heat-producing components. When the cover is closed, the ambient temperature underneath is kept close to the outside temperature; this eliminates any heat exchange, which would produce turbulence in the light coming from the sky into the telescope. 
 
 
 

Credit line: "Canada-France-Hawaii Telescope / 2003"

Copyright © 2003 Canada-France-Hawaii Telescope Corporation