Development of a Correlation Tracker and a Tip-Tilt Mirror System for SOLAR-B

The solar observation satellite “SOLAR-B,” which is being developed under the joint cooperation of JAXA and NAOJ with the U.S.A. (NASA) and the U.K. (PPARC), will be launched in summer 2006. SOLAR-B requires very high pointing stability for its three telescopes. In particular, the Solar Optical Telescope (SOT), which has the highest resolution and narrowest field of view among these telescopes, requires 0.06 [arcsec]3σ of short-term (10[s]) stability to meet the observation demands. However, it is very difficult to achieve such levels of stability by only using the satellite attitude control system due to disturbance from the observation equipment. Therefore, we propose using the Correlation Tracker and tip-tilt Mirror package (CTM), which stabilizes the sun observation image. CTM consists of a correlation tracker and a piezo-based tip-tilt mirror with servo control electronics. This paper describes the mechanism and the control and determination methods of the control gain of CTM as well as the results of experiments conducted to clarify its capability.