In ESA, set the clock for distant pulsars

In ESA, set the clock for distant pulsars

Pulsar enclosed in a supernova bubble

The ESA Technical Center in the Netherlands began using a pulsar-based watch. The PulChron system measures the passage of time using millisecond radio pulses from several rapidly rotating neutron stars.

The measurement system has been operating since the end of November and relies on current observations from 5 radio telescopes throughout Europe. Neutron stars are the densest form of observable matter in space, formed from the collapsing core of exploding stars. These objects cover only tens of kilometers in diameter, but surpass the sun in mass.

A pulsar is a type of rapidly rotating neutron star with a magnetic field that releases rays from the poles. Rotation remains stable due to extreme density; therefore, regular radio bursts are observed from the Earth. PulChron aims to prove the effectiveness of a pulsar-based time scale for generating and monitoring satellite navigation time in general and Galileo system time in particular.

In ESA, set the clock for distant pulsars

Atomic clocks in the ESTEC navigation laboratory: in the right-hand corner are the atomic clocks in the active hydrogen maser, which are an order of magnitude more accurate than the passive hydrogen masers aboard each Galileo satellite. Additional cesium clocks are shown on the left, as well as a system for comparing clocks and distribution

In the short term, the time scale based on pulsars is usually considered less stable than an atomic or optical clock. But if we talk about a long period, it is a strong competitor. In addition, the time scale of the pulsar functions independently of the atomic clock technology used. That is, it is not based on switching between the state of atomic energy, but on the rotation of neutron stars. PulChron receives measurement groups from 5 radio telescopes of the 100-meter class. Thus, it is possible to track 18 high-precision pulsars in the European sky in order to fix any temporary anomalies and potential evidence of gravitational waves. These measurements are used to control the output of atomic clocks with an active hydrogen maser.

In ESA, set the clock for distant pulsars

PulChron system setup - setting an atomic clock using pulses of a millisecond scale from rapidly rotating pulsars. Radio-telescopic measurements are used to control the output of atomic clocks with an active hydrogen maser with equipment based on the ESA synchronization and geodetic check tool

The accuracy of the PulChron is controlled to an accuracy of several billionths of a second with the help of the Coordinated Universal Time of the ESA laboratory, using 3 atomic hydrogen maser sensors, in addition to three cesium clocks. All this allows to obtain a highly stable synchronizing signal.

Thus, it is possible to track the gradual deviation of the pulsar time from ESTEC coordinated universal time. Forecasts indicate a speed of 200 trillionths of a second per day.

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