a
Mountain Laboratory, and the terrestrial backup
ground photography was made by EG&G in conjunction
with Project 13.2.
Analysis and reporting of the data were the responsibility of EG&G. One RB-36 and three C-54 aircraft
participated in the aerial photography and flew a total
of six missions per aircraft. Usable results were
obtained from two or more aircraft on all events except for Shot 3, where photo results were negative
due to natural cloud cover obscuring ground zero.
Preliminary analysis of the Castle cloud data indicated
excellent results for the period of H + 10 minutes.
Aerial oblique photography supporting Project 3.2,
Crater Survey, was flown by Lookout Mountain Laboratory personnel.
for Shots 4 and 5; this barge was 62,200 tcet from the
shot barge for cach of these shots. For Shot 6, the
bolometer was mounted on a power house on Yvonne
Island, 77,522 feet from the shot barge.
The modulated bolometer consistec! of two blackened platinum wires whose resistance changed with
temperature.
One wire was in each cf two arms of a
Wheatstone bridge, which with 4 mechanically driven
chopper alternately exposed first onc wire and then
the other wire to the thermal radiation.
The applica-
tion of a de voltage at one end of the bridge resulted
in an ac output at the other end that was amplified
and recorded on magnetic tape.
Total tuermal energy was measured by use of
This mission consisted of a
Epply thermopiles faced toward the detonationsite.
serics of aerial photographs tracking an LCU during
The output of the thermopiles was recorded on Brown
recording potentiometers. These thermopiles were
located un Tare, How, and George Islands for Shots
i and 2. They were located on Nan Island and on 2
barge near How Island for Shots 4 and 5; for Shot 6,
they were located on Fred and YvonneIslands.
Army Map Service for Project 3.2.
Project 18.3 “High-Resolution Spectroscopy”
(WT-950), Naval Research Laboratory; H. Stewart,
Project Officer.
the period of time fathometer readings were being
made in the Shot 1 crater.
Preshot and postshot crater vertical acrials were
flown on Shots 1 and 3 by Strategic Air Command
reconnaissance personnel. Analysis of the crater
dimensions was made from this photography by the
Technical still photography requirements in support
of DOD projects were met entirely by Los Alamos
Scientific Laboratory photographic personnel. All
project requirements were coordinated and programmed through Program 9, including preshot and postshot photography.
PROGRAM 18: THERMAL RADIATION
MEASUREMENTS!
Project 18.2, Project 18.5 “Thermal Radiation”
Naval Research Laboratory; H. Stewart, Project
Officer.
- For Shots 1, 2, 4, and 5, spectrographs of various
dispersions and in selected wave-lengih ranges werc
located in a concrete bunker at the base of a 200-fou.
tower on the south end of NanIsland Mirrors on the
tower reflected light from the detonations t> the viewing slits of the spectrographs. For Shot 6, spectrograph installations were established on Fred and
Janet Islands.
Project 18.4 “Atmospheric Transmission of Light”
Naval Research Laboratory; H. Stewart, Project
Power-versus-time measurements were made by
employment of modulated bolometers. These bolometers were located in 8~by-2-by-8-foot coffins mounted on photo towers on How and Tare Islands for Shots
land 2. The How tower was 97,975 feet and the Tare
tower 77,765 feet from ground zeroof these shots.
The bolometers were mounted on a barge near How
'Not a formal DOD program. These thermal-radiation
projects of DOD interest were sponsored by LASL
(see Chapter 8). Publication information for Projects
18.2, 18.5, and 18.4 is as yet uncertain; information
on their availability and the availability of the Project 18.3 final (WT) report may be obtained from
LASL.
118
Officer.
Atmospheric transmissicn was measured over
selected paths. To make these measurements, a
searchlight of known luminous intensity was mounted
near each zero site for cach selected path andtrained
on a photocell receiver at the other end of the path.
The searchlight beam was modulated by a mechanicalchopper (60 cps) and the receiver system was arranged so that only light at this modulated frequency
was received, thus making the system independentof
daylight.
The paths for each shot were: Shot 1, from
zero site to George, Tare, and Delta Islands (Delta
is an artificial island near Able); Shot 2, from zero
site to George and Tare Islands; Shots 4 and 5, from
zero site to How and Nan Islands; and Shot 6, from
zero site to Fred and Janet Islands.