The paper
Jocelyn Bell, a postgraduate at Cambridge, helped build a radio array and then walked the charts it produced. In 1967 a bit of scruff kept returning from the same place in the sky.
On 28 November a faster recorder showed it clearly: pulses, 1.337 seconds apart. Too regular for ordinary radio noise. Too natural, once checked, to be a nearby machine. They called it CP 1919: Cambridge pulsar at right ascension 19h 19m.
ASTRONOMY
A pulsar is a neutron star whose beam of radio radiation sweeps the Earth as it spins. Periods can be used as clocks. Later proposals include pulsar navigation for spacecraft. That is a sequel, not the 1967 paper. Nature printed “Observation of a Rapidly Pulsating Radio Source” on 24 February 1968.
After
The first four Cambridge pulsars followed. The sky had a new kind of dead star that still kept time. Bell Burnell has spent decades being asked about the prize she did not receive. The chart remains the event. The prize is a later argument about credit.
Question
What kind of star is a clock you can hear but not, at first, see?