On May 7, 1952, Los Angeles residents welcomed two dawns. The first occurred at 5:15 a.m. — a flash from a Nevada nuclear device test. Forty-three minutes later, the real dawn arrived.

A story in the next morning's Los Angeles Times reported:

The first predawn atomic flash since early 1951 over the Nevada proving ground was visible clearly from Los Angeles yesterday morning.

Despite a cloudy sky, the intense brilliance carried 300 miles between here and the atomic test site to fringe downtown buildings in a brief aura of fierce light.

Photographs taken from Civic Center show the northeastern sky luminous from a man-made sunrise. The detonation was at 5:15 a.m. — 43 minutes before dawn.

The five experimental nuclear explosions early last year all occurred in morning darkness. The 12 others which followed, with the exception of yesterday's, came in bright sunlight .…

Observers at the control tower at International Airport described the sight as resembling bluish lightning. The flash observed here was instantaneous. No afterglow was discernible.

This photo was taken from a balcony at the Los Angeles Times building and published in the May 8, 1952, edition. The light ray from atop City Hall is from the Lindbergh Beacon.

The Partial Test Ban Treaty in 1963 banned atmospheric testing of nuclear weapons.

This post was previously published on Oct. 3, 2013.

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