This information is derived from nuclear burst reports submitted by
reporting units. The providing of correct data requires both knowledge and
attention to procedures by personnel of the reporting unit.
interested in obtaining a quick "gross" fix on the location of ground zero
(GZ) for any nuclear burst that is close enough to be observed.
information is used by the commander in making an estimate of the situation
and in determining what impact, if any, the burst will have on executing the
The location of GZ may be determined in several different ways
simultaneously at the various levels of command. Locally, the commander may
be able to ascertain location of GZ of very small nuclear explosions by
direct observation. If so, the GZ location will be reported as indicated in
the NBC 1 (Nuclear) report.
For larger yields and more distant nuclear bursts, the unit can use the
azimuth and flash-to-bang distance from its observation point to determine
GZ location. Generally, units reporting large nuclear detonations will be
from 10 to 50 kilometers (km) from ground zero. They will report flash-to-
bang time, coordinates of observer location, and azimuth to the nuclear
burst cloud along with other items specified in the nuclear burst report.
This data will be plotted by the NBCC and the GZ locations determined from
intersecting azimuths from two or more observation points.
data is incomplete, GZ location can also be determined from intersecting
arcs using radii of flash-to-bang distances from two or more observation
Ground zero will normally be determined by the NBCC from the
intersection of azimuths from two or more observation points using report
data corresponding to the same date and time of detonation. Combinations of
arcs using radii of flash-to-bang distances and azimuths from observation
points can also be used.
Nuclear Cloud Development.
Development of nuclear clouds is divided into three stages for the purpose
of yield estimation.
The fireball stage exists from the instant of
detonation until the generally spherical cloud of explosion products ceases
to radiate a brilliant light.
During this stage the fireball must not be
observed because the very brilliant light is capable of causing permanent
damage to the eyes. As the brilliant light fades into a dull reddish glow,
the fireball stage transforms into the nuclear burst cloud stage.
nuclear burst cloud stage begins when the light of the fireball has faded to
the point that the cloud from the explosion can be safely observed by the
unprotected eye. At this time the nuclear burst cloud may be seen as either
a spherical cloud (high