d. Illumination Time.
As a field expedient, yield may be estimated from the measurement of the
illumination time of a nuclear burst, especially during hours of darkness or
However this method should be used only if it is
impossible to obtain cloud parameters as discussed, since this method only
gives a yield estimate on the order of a factor-of-10.
measuring illumination time will vary, depending on the situation, but under
no circumstances should the observer attempt to look directly at the
fireball since this can result in permanent damage to the eyes.
a foxhole by noting the light reflected into the foxhole. The observer can
look at the floor of the foxhole and still sense the duration of the flash
or reflected light. Counting in seconds will probably be the most effective
way of determining the illumination time since the "dazzle" (flash
blindness) effect will preclude the reading of watches.
Nuclear Yield Calculator.
The M4A1 Nuclear Yield Calculator, a component of the M28A1 Nuclear
Calculator Set, is designed to provide a rapid method for calculating
nuclear yield from a nuclear burst. The old M4 Nuclear Yield Calculator, a
component of the M28 Nuclear Calculator Set, should not be used because it
gives a yield estimate that is inaccurate.