The photometers of the Synchronous Network of distant Telescopes need time keeping relative to UTC with accuracy no less than 1/10 of the resolution time. The time-keeping system (TKS) uses Acutime 2000 GPS Antenna for Precise Timing and Synchronization. TKS carries out measurement of rising edge of an external event pulse by its binding to a pulse-per-second (PPS) output synchronized to UTC within ±100 nanoseconds. TKS provides:

The lapse of time of the secondary time source (CH7-15) is equal to about 1 millisecond per day (the top panel).
TKS output synchronized by PPS shows the lapse of time within 1 microsecond (the lower panel).

(Svyatogorov O., Sergeev A., Gavriliuk Yu.,
Zhilyaev B., Romaniuk Ya.)