A pulsar clock is a clock which depends on counting radio pulses emitted by pulsars.
An international team of astronomers came up with a new way of keeping track of time by observing a collection of pulsars, which are rapidly rotating stars that emit radio pulses at very regular intervals.
Originally the research was to use pulsar timing to detect gravitational waves, but more study has shown that the pulsar-based timescale can also be used to reveal inconsistencies in timescales based on atomic clocks.
Pulsars are neutron stars that rotate at very high speeds and appear to emit radio pulses at extremely regular intervals. The pulses are actually all we see of a radio beam that is focused by the star’s magnetic field and swept around like a lighthouse beacon.
They are the rapidly spinning and highly magnetized core left behind when a massive star explodes. Because only rotation powers their intense gamma-ray, radio and particle emissions, pulsars gradually slow as they age. But the oldest pulsars spin hundreds of times per second — faster than a kitchen blender.
Using a radio telescope, astronomers can measure the arrival times of successive pulses to a precision of 100 ns over a measurement time of about an hour. While this level of precision is significantly less than that offered by an atomic clock, pulsars could in principle be used to create timescales that are stable for decades, or even centuries.
This could be useful for identifying fluctuations in Earth-based timekeepers such as atomic or optical clocks, which normally do not operate over such long periods.
CSIRO Astronomy and Space Sciences in Australia, looked at data from the Parkes Pulsar Timing Array (PPTA) project. Using the Parkes radio telescope in Australia, the project used a set of 17 pulsars in different parts of the Milky Way to detect gravitational waves.
The idea is that when a gravitational wave passes through our galaxy, its presence warps space/time such that the millisecond gaps between the pulses arriving from various pulsars are affected in a very specific way.
Radio astronomers discovered the first millisecond pulsar 28 years ago. The first pulsar clock in the world was installed in St Catherine’s Church, in Gdańsk, Poland, in 2011. It was the first clock to count time using a signal source outside the Earth.
The pulsar clock consists of a radiotelescope with 16 antennas, which receive signals from six designated pulsars. Digital processing of the pulsar signals is done by an FPGA device.
A display showing the exact time of the pulsar clock was installed in the European Parliament in Brussels, Belgium.