How to watch a nuclear explosion

VIP observers watching the spectacle during Operation Greenhouse at Enewetak Atoll, 1951.
Soldiers being exposed to a nuclear explosion at the Nevada Test Site in 1951.
Believe it or not, these five volunteers were standing at ground zero when a 2KT nuclear war headed air-to-air missile, Genie, was exploded 15,000 feet above their heads, to demonstrate that the weapon was safe for use over populated areas. Whether this affected the health of the officers is unknown.
The testing of "Small Boy" in 1962
Cameramen at the Nevada Test Site, May 25, 1953
Troops watching during Operation Tumbler-Snapper. Twenty-one hundred marines participated in this test on May 1, 1952
Crew of the USS Fall River watching the atomic blast during Operation Crossroads in 1946

Casual observers of the Baker blast during Operation Crossroads

The origin of the next two pictures is unknown, though the last one could be from Operation Tumbler-Snapper.