Stereo observations using SST-1M telescopes

SST-1M Cherenkov telescopes installed within the Ondřejov observatory of the Astronomical Institute of the Czech Academy of Sciences observing high-energy gamma photons have reached another technical milestone. In March 2023, the White Rabbit system was implemented, enabling accurate relative or absolute time synchronisation of both telescope systems.

White Rabbit (WR) enables the synchronization of internal clocks of network components with nanosecond (or better) accuracy. The WR SST-1M telescope system synchronizes the internal clocks of both Cherenkov telescope cameras via an internal optical network. The distance between the two telescopes is 151 m and precise time synchronization is necessary for the coincidence of measured events and the merging of showers generated by one particular particle at both telescopes. The principle of selection of coincidence events using the CTA software array trigger - SWAT fundamentally reduces the amount of measured data by selecting the time sequence of two events with a defined time offset (typically hundreds of nanoseconds). Furthermore, this method enables the improvement of the energy calibration, the angular resolution of the measured data, and the reduction of the night sky background.

The experts of the Joint Laboratory of Optics significantly contribute to the development of the system.

Stereo detection of a coincidence event of the Mrk 421 gamma ray source using two SST-1M telescopes and the time evolution of the shower in the field of view of both telescopes. Mrk 421 (Markarian 421) is an active galaxy (blazar) in teh constellation Ursa Maior about 397 mil. light-years from Earth and its galactic nucleus suspected to contain a supermassive black hole is a strong source of gamma rays.