OSCAR 1, the first amateur satellite, was launched on December 12, 1961, just four years after the launch of world's first satellite, Sputnik I.
It was the first satellite to be ejected as a secondary payload and subsequently enter a separate orbit. Despite being in orbit for only 22 days OSCAR 1 nearly 600 amateur radio operators in 28 countries forwarding observations to Project OSCAR.
It was launched on an Agena B rocket from Vandenberg AFB in California along with a Discoverer series satellite. KC4USA in Antarctica first reported signals as it passed over there after being launched. Oscar 1 was battery powered.
The batteries were not rechargeable and its signals lasted for about two weeks. The transmissions were on 145.00 MHz and the CW signal repeatedly sent HI in morse code. The number of HIs per minute, or the “HI Rate” was the only telemetry sent. The HI Rate gave the internal package temperature and amateurs were asked to report the HI rate.
For more information see the AMSAT website.