page_title: Pulsar
section_title: History of observation
hierarchical_section_title: Pulsar / History of observation
caption_attribution_description: English: The chart examined by Jocelyn Burnell in August 1967 with data from the 4 Acre Array radio telescope, showing the trace of the first identified pulsar, subsequently designated PSR B1919+21
context_page_description: A pulsar is a highly magnetized rotating neutron star that emits beams of electromagnetic radiation out of its magnetic poles. This radiation can be observed only when a beam of emission is pointing toward Earth, and is responsible for the pulsed appearance of emission. Neutron stars are very dense, and have short, regular rotational periods. This produces a very precise interval between pulses that ranges from milliseconds to seconds for an individual pulsar. Pulsars are one of the candidates for the source of ultra-high-energy cosmic rays.
  The periods of pulsars make them very useful tools for astronomers. Observations of a pulsar in a binary neutron star system were used to indirectly confirm the existence of gravitational radiation. The first extrasolar planets were discovered around a pulsar, PSR B1257+12. In 1983, certain types of pulsars exceeded atomic clocks in their accuracy in keeping time.
caption: Chart on which Jocelyn Bell Burnell first recognised evidence of a pulsar, exhibited at Cambridge University Library
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