http://www.lacrossetechnology.com/8117it/manual.pdf This has the instructions for your atomic clock.

Trinity was the code name for the explosion of the first atomic bomb in New Mexico in 1945.

Hiroshima and Nagasaki.

An atomic clock is a reference clock whose operation is based on an atomic process, such as the frequency of electromagnetic radiation associated with a specific energy-level transition in an element such as caesium.

The US would have invaded Japan on 01 Nov 45 Operation: DOWNFALL.