Discovery of PSR 1913+16
The Binary Pulsar PSR 1913+16 was discovered using the Arecibo 305 meter radio antenna.
It is about 5 kpc away near the boundary of the constellations Aquila and Sagitta.
This pulsar rotates 17 times
a second, giving a pulsation period of 59 milliseconds.
The discovery that it was a member of a
binary followed the observation of a cyclic variation in the arrival time of the pulses,
first sooner and then later than expected, repeated on a 7.75 hour cycle. This would be
expected if the pulsar were part of a binary system with a 7.75 hour period.
Other such binary pulsar systems have since been discovered. However, it is common to refer to
PSR 1913+16 as The Binary Pulsar.