The Earthshine Telescope Project

Abstract:
The Earthshine telescope project is a collaborative effort between Lund Observatory (LO) in Sweden and The Institute of Meteorology in Demark (DMI) with the purpose of constructing one or more robotic telescopes to record the albedo of the Earth over a long time. The objective is to measure long-term development of the global cloud coverage and reflectivity for climate modeling. A 1% change in the Earth's albedo will result in an average temperature change of 0.5 K of the Earth, calling for high precision of the albedo measurements. This poses strict demands on the telescope design, in particular with respect to suppression of straylight. The paper describes our proposed optical and mechanical design of the Earthshine telescope, and presents a preliminary straylight analysis of the design.