Dim-star Tracking for Stellar Interferometry

This paper proposes a new dim-star angle tracking architecture applicable to multibaseline stellar interferometry missions like Space Interferometry Mission (SIM). The proposed architecture is being implemented on SIM´s system test bed 3 (STB3) - a 3-baseline stellar interferometer test bed with similar instrument architecture to that of SIM. Preliminary implementation results, analysis and traceability to the flight system are discussed. The proposed dim-star tracking architecture consists of feeding angle tracking information from one of the guide interferometers´ back-end cameras to the fast steering mirror on the science interferometer. The information would allow the science interferometer to track its own dim-star, while not having the needed photon-rates to use its own camera as a sensor. One of SIM´s requirements for STB3 is to show 20 dB of rejection of induced motion at any frequency between 0.1 and 1 Hz. This level of performance has been reached and is discussed in the results at the end of this paper