PSR B1919+21

Via Wikipedia

PSR B1919+21 is a pulsar with a period of 1.337 seconds and a pulse width of 0.04 second. It is notable for being the first radio pulsar ever discovered (in July 1967 by Jocelyn Bell Burnell). Its original designation was CP 1919 and it is also known as PSR J1921+2153. It is located in the constellation of Vulpecula.