The Fine Guidance Sensors System (FGS) is intended for precise pointing and stabilization of the telescope during a scientific observation session.

The Fine Guidance System consists of 3 guiding sensors located near the central part of the telescope focal surface, and the common Data Processor Unit (DPU). Every sensor is based on 1 megapixel rad-hard CMOS image sensor STAR 1000, fabricated by Fillfactory.The Master catalogue for the Fine Guidance System is stored in the Data Processor Unit and contains coordinates of guiding stars over all the sky up to 17 magnitude.

Fig. 1 Rad-hard CMOS image sensor STAR 1000 for Fine Guiding system.

Sensitive surfaces of guide sensors are located close to the spectrographs entrance slits on their cases. It provides high stability of mutual position of the entrance slits and GS receivers.

Main characteristic of FineGuide system are presented in the following table