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,
EVENT
OPERATICN H'RDTACK
1.
ELDER was detonated at 0630M on a barge one mile southwest of
Janet Island, Enivetok Atoll, on 28 June 1958,
The cloud rose nore
rapidly than usual and passed beyond the upper limit of the weather radar
(50,000 feet) at H+2 minutes and 50 seconds.
No cloud height observations
from aircraft were readily aveilable, and it was not until H+50 minutes
that a cloud sampler reported the top ain This figure wouldy
indicate that the initial cloud height was probably well —
2,
Cloud -ovement was generally to the north, with stem movement
to the weste-northvest.
Net movement was slow; in fact, the upper eloud
(above 50,000 feet) could be observed directly over the atoll for several
hours >
3.
The P2V arrived at H+30 minutes and cleared tha lagoon south of
a line from Yvonne to Leroy by H+1.
The rest of the lagoon was cleared
by H+2k except for the islands from Alice to \ilma, and re-sntry hour was
declared by 143.
4s
FOFU predicted a fallout plot between the radials 270 degrees to
320 degrses.
The actual pattern was from 260 degrees to 010 degrees, with
e4
L
Wy
ores
the extent essentially as predicted.
TAB A
1