CRYOGENIC SOLAR ABSOLUTE RADIOMETER (CSAR)

The Cryogenic Solar Absolute Radiometer (CSAR) is a new primary radiom etric standard for use in space and traceable to the International Sys tem of Units (SI). The CSAR will be capable of measuring the total irr adiance of the Sun with an uncertainty of 0,01 %, and a resolution of 0,001 %, more than a factor of ten improvement over existing instrumen ts. The standard is at present under development and is part of a prop osal, Absolute Radiometric Measurements in Space (ARMS), which has bee n submitted to the European Space Agency in response to a Call for Opp ortunities for Columbus Pre-Cursor Flights. The CSAR is currently on t he provisional payload of EURECA III.