Link here. It also happens to have been the fourth ever launched, and the second U.S. satellite, Vanguard 1.
Thanks to Kirk for reminding me that Vanguard 1 was not the first U.S. satellite, and was actually the fourth launched, not the second. All I needed to do to avoid the error was read my own Chronological Encyclopedia, but I was too lazy to do that, even though it is on my desk. Duh.