Recent results of the Guide-2 telescope testbed for the SIM-Lite mission

The Space Interferometry Mission Planet Quest Lite (SIM-Lite) is a new mission concept to perform micro-arcsecond narrow-angle astrometry to search approximately 50 nearby stars for Earth-like planets, and also to perform a global astrometry. The SIM-Lite consists of two Michelson interferometers and one telescope. The main six-meter baseline science interferometer observes a target star and a set of reference stars. The four-meter baseline interferometer (Guide-1) monitors the attitude of the instrument in the direction of a target star. A new Guide-2 telescope (G2T) tracks a bright star to monitor the attitude of the instrument in the other two orthogonal directions. In the current mission concept, the G2T consists of a 30 cm siderostat and a 30 cm confocal telescope, similar to other four telescopes used in the science and Guide-1 interferometers. A testbed has been built to demonstrate the G2T feasibility for SIM-Lite mission. Recent results show that field-independent, star-tracking capability of the system is less than 30 mas after the SIM narrow angle analysis.