In the first (and only) shipboard launch conducted during the Viking sounding rocket program, Viking 4 is launched from the deck of the USS Norton Sound near Jarvis Island in the Pacific (0.19 N 161.42 W), 11 May 1950, 1608 local time, at the intersection of the geographic and geomagnetic equators. The rocket reached an altitude of 105 miles (169 km), an altitude record for an American single-stage rocket and almost the maximum possible for the payload flown, in a nearly perfect flight. Onboard equipment included cosmic radiation measurement, and upper-air pressures and temperatures research.