surveyed diameters.
The craft t sed was an LCM, and its position at the tituc the sound-
ings were made was determined Ly Raydist.
The use of Raydist to establisl. the horizontal control location of the lead-line sound-
ings had been previously planned to preclude the need for postsurvey personnel to land
on Site Tare to accomplish the horizontal control by conventional survey triangulation
methods. The Raydist equipment was already available, because of other Project 5.6
aircraft-tracing requirements. It was considered that the elimination of the need of survey personnel to land on Tare, with its expected relatively high postshot radiological
contamination, would permit an earlier crater-depth survey by at least several days.
Because of the rather severe postshot tidal-wash action expected through the Zuni crater
area, which would possibly modify the initial crater m:asurements considerably, it was
obviously desirable that the postshot lead-line soundings be made as soon as possible
after the shot.
The position of ground zero was determined before shot time by Raydist, and the LCM
craft was guided to this spot for the beginning of each run along the radii.
the craft along these radii was governed by compass direction.
2.2.3 Seminole, Mohawk, and Tewa.
The course of
Residual radiation was too high for detailed
soundings to be made of these cratcrs while the operation was in progress. Soundings
were taken from a helicopter at ground zero for Seminole and Mohawk and reported in the
preliminary report. Lead-line soundings made by Holmes and Narver in September and
October 1956 are reported in Chapter 3 of this report.
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