MAGEOLIAEVENT
OPERATION HARDTACK
40
The MAGNOLIA device was detonated st COOOM, 27 May 1958, 3,000
rset southisst of tha center of Yvonne Island.
The cloud rose immediately
to 44,000 feet and stabilized at 41,000 feet with the base at 15,000 fest.
Radar confirmed this ncesition, and ths initial cloud movement was westerly.
The middle segment ramained over ground zero, and the upper and lower
levels moved on a bea-ing of 250 degrees,
2.
The P2V aircraft was vectored from Alvin to Keith at 0633M, and
it reported reaaings of Zero at 500 feat.
The northern chain was then
surveyed, with the highest reading recornied over Alice:
5 mr/hr, at O647M,
Tne lagoon area was swept in 10edegres increments, and in the center of the
lagoon at 500 fest, 7 r was recorded at 0735M,
The aircraft vas considered
contaminated and was instructed to wash jicwn at Fred.
FPeentry was declared
at 0730M,
30
A helicopter ground survey was initiated at 0745M,
The higheat
rogding wes recorded at Alice, with 22,CCO mr/hr, which 1s attributed to
the YELLCWWOOD event.
Other islands in the northern chain ranged ffon
2 nz/hr to 120 mr/nr, with Yyonne reading 1,200 te 2,000 mr/nr.
4.
A second helicopter survey wae made at 1430M.
The southern chain
indicated only background with tha exception of Leroy, which r2ad 35,000 mr/rh
at twenty-five feat.
This high reading is attributed to a small section of
the cloud which did not move out of the legcon as anticipated.
This high
rexding accounted for the contamination of the Pav, BEST CUP} \¥ VILABLE
TAB A
J2i