3 Active Hydrogen Masers and 3 Cesium atomic clocks.
You can synchronize your computer’s clock to our facility UTC(ESTC) by using the following NTP server address “time.esa.int”
The UTC facility hosts and operates a set of high performance atomic clocks (H-Masers, Cs) and generates a timescale traceable to UTC. The performance of this timescale is reported every month by the BIPM in the Circular T. The operation and performance of these clocks are continuously monitored using phase comparison (10 MHz), time interval counters and calibrated GNSS receiver chains. The UTC(ESTC) signal is distributed to the whole Laboratory through 10 MHz and 1 pps signals.