PSR B1919+21 is a pulsar with a period of 1.3373 seconds and a pulse width of 0.04 second. It was the first radio pulsar discovered (in July 1967 by Jocelyn Bell Burnell). The original designation of this pulsar was CP 1919 and it is also known as PSR J1921+2153. It is located in the constellation of Vulpecula.
Read more about PSR B1919+21: Discovery, Nobel Prize Controversy, Cultural Reference