A Graduate Student Discovers the First Pulsar

On about 28 November 1967, a fast chart recorder at the Mullard Radio Astronomy Observatory near Cambridge captured the unusual signal that Northern Irish postgraduate researcher Jocelyn Bell had been tracking for months. She had spent the previous two years helping assemble the Interplanetary Scintillation Array, an expansive radio telescope designed by her doctoral supervisor Antony Hewish to monitor quasars. Bell inspected chart recorder rolls by hand, examining miles of paper tracking radio sources across the sky, working through roughly thirty meters of chart paper each day. In August, amid the recorded noise, she had noticed a faint, flickering trace she called scruff, and she found that it returned at the same sidereal time, moving with the stars rather than with local terrestrial time.

After she raised the trace with Hewish in late August, a faster chart recorder was installed, but the source then failed to appear for weeks. When it returned in late November, the new recording showed that it was not random static, but a series of short pulses repeating about every 1.337 seconds. The source was jokingly nicknamed LGM-1, for Little Green Men, reflecting playful speculation about potential extraterrestrial origins, before further astrophysical study established that the emission came from a natural, rapidly rotating neutron star, later designated PSR B1919+21.