Pre-flight calibration of LYRA, the solar VUV radiometer on board PROBA2

¹ Royal Observatory of Belgium, SIDC, Circular Avenue 3, 1180 Brussels, Belgium e-mail: ali.benmoussa@oma.be
² Solar Terrestrial Center of Excellence (STCE), Circular Avenue 3, 1180 Brussels, Belgium
³ Max-Planck-Institut für Sonnensystemforschung, 37191 Katlenburg-Lindau, Germany
⁴ Physikalisch-Meteorologisches Observatorium Davos – World Radiation Center, 7260 Davos Dorf, Switzerland
⁵ Centre Spatial de Liège, Av. Pré Aily 4031 Angleur, Belgium
⁶ Physikalisch-Technische Bundesanstalt (PTB), Abbestr. 2-12, 10587 Berlin, Germany
⁷ LPCE, UMR 6115 CNRS-Université d'Orléans, 3A Av. de la Recherche Scientifique, 45071 Orléans Cedex 2, France
⁸ Royal Meteorological Institute of Belgium, Circular Avenue 3, 1180 Brussels, Belgium
⁹ Belgian Institute for Space Aeronomy, Circular Avenue 3, 1180 Brussels, Belgium

Received: 7 August 2009
Accepted: 25 October 2009

Abstract

Aims. LYRA, the Large Yield Radiometer, is a vacuum ultraviolet (VUV) solar radiometer, planned to be launched in November 2009 on the European Space Agency PROBA2, the Project for On-Board Autonomy spacecraft.

Methods. The instrument was radiometrically calibrated in the radiometry laboratory of the Physikalisch-Technische Bundesanstalt (PTB) at the Berlin Electron Storage ring for SYnchroton radiation (BESSY II). The calibration was done using monochromatized synchrotron radiation at PTB's VUV and soft X-ray radiometry beamlines using reference detectors calibrated with the help of an electrical substitution radiometer as the primary detector standard.

Results. A total relative uncertainty of the radiometric calibration of the LYRA instrument between 1% and 11% was achieved. LYRA will provide irradiance data of the Sun in four UV passbands and with high temporal resolution down to 10 ms. The present state of the LYRA pre-flight calibration is presented as well as the expected instrument performance.