Map of the Operation Crossroads A-bomb test at Bikini Atoll, annotated by a witness!

DISPOSITION OF PLANES AT MIKE HOUR. [Probably the South Pacific, near Bikini Atoll, mid-1946].
13”h x 18”w, uncolored, with manuscript annotations in ink. Old folds and a bit of creasing and toning, but better than very good.

Unrecorded map of the “disposition of planes” around Bikini Atoll during the first atomic bomb test of Operation Crossroads on July 1, 1946, with annotations by an observer at the scene. An extraordinarily rare and oddly-charming relic of a not-very-charming event.

Operation Crossroads was the first test of an atomic weapon since the July 1945 “Trinity” test, which had of course preceded the bombings at Hiroshima and Nagasaki. Located at Bikini Atoll in the southwest Pacific, the operation was to comprise three separate detonations: “Able” was an airburst on July 1, 1946; and “Baker” was an underwater blast on July 25; while “Charlie”, a deepwater explosion planned for 1947, was canceled altogether. Unlike Trinity, Crossroads was announced in advance, and the press and other guests were invited to observe.

Offered here is a map produced just before the Able test, depicting a radius of roughly 17 miles around the Atoll, with two dozen silhouettes indicating the planned locations of two dozen support planes at “Mike Hour”, the moment of detonation. This possibly unique example is rendered yet more interesting by the presence of ink annotations added by a sailor or member of the press stationed on the USS Appalachian. This was an amphibious force flagship launched in 1943 and had previously seen service at Kwajelein, Guam, and the Philippines before being designated as the press headquarters for Operation Crossroads. In that role it was to be positioned northeast of the Atoll, some 14 miles or so from the blast.

In the southwest corner of the map the anonymous annotater has added “B-29 carrying “A” Bomb comes in here,” with an arrow pointed toward the atoll, over which is drawn a bullseye labeled simply “Target”. At upper right a small ship symbol represents the Appalachian, with the notations “We’ll be here when she bursts” and “15 mile range”. And at lower right is a scribbled windhead blowing to the southwest, with the label “Wind blowing this way—we hope!” This last addition demonstrates that the notations were made in advance of the Able blast.

A member of the Associated Press stationed on the Appalachian sent a variant version of the map stateside, and the image was published in newspapers around the country. For example, it was reprinted in the San Pedro News Pilot, with the note that “This chart sent by radiophoto from the USS Appalachian in the Bikini area shows the disposition of various aircraft at the time of the atom blast scheduled for July 1.” (San Pedro News Pilot for June 27, 1946, p. 5) However, I have been unable to locate any other examples of the larger, separately-issued map offered here.

The map is not recorded in OCLC, and I find no record of its having appeared on the antiquarian market.