Title: Gravitation Astrometric Measurement Experiment (GAME)

　　Speaker: Mario Gai (Turin astronomical observatory, Italy)

　　Time & Place: Tuesday, 2:30pm, March 4th, 3rd floor middle conference room

　　Abstract:

　　The Gravitation Astrometric Measurement Experiment (GAME) is a space mission for Fundamental Physics tests in the Solar system, using coronagraphy and Fizeau interferometry techniques for differential astrometry among superposed stellar fields. The main goal is verification of the General Relativity (GR) and competing gravitation theories in the weak field of the Solar System by high precision measurement of the light bending in the vicinity of the Sun and of the main and minor planet dynamics.

　　The GAME payload concept is based on a single main telescope (1.5 m diameter) implementing multiple aperture Fizeau interferometry, observing simultaneously four regions close to the Solar limb; coronagraphic techniques are applied on the elementary sub-apertures. The diluted optics approach is selected to achieve an efficient rejection of the scattered solar radiation, while retaining an acceptable angular resolution on the science targets. The background is fundamentally limited by the Corona at 2° from the Sun centre, to ?9 mag per square arc sec.

　　The star displacement due to light deflection is derived by differential astrometry on images taken at different (deflection ON and OFF) epochs. The measurement is naturally focused on the high stellar density regions of intersection of the Ecliptic and Galactic planes, scanned in about 1 month following the sidereal projection of Earth’s orbital motion.

　　The instrument design is focused on systematic error control through multiple field simultaneous observation and calibration.