Previous: Atmospheric extinction
Up: Exposure times
Next: Spectrograph efficiency
Previous Page: Atmospheric extinction
Next Page: Spectrograph efficiency

Telescope efficiency

Light is lost at each reflection from an aluminised telescope mirror. It is difficult to quantify this precisely, since the reflectivity of the mirror degrades with time, but a value of 85 per cent for the reflectivity would be a reasonable estimate.

Wed Apr 6 22:56:39 BST 1994