  We present a careful statistical analysis of pulsating aurora (PA) using
all-sky green line (557.7 nm) images obtained at 3.3 Hz. Six well-defined
individual PA patches are identified and extracted using a contouring
technique. Quantitative parameters such as the patch duration (on-time and
off-time), peak intensity, and integrated intensity are determined for each
patch and each pulsation. The resulting characteristics serve as strict
observational constraints that any of the many competing theories attempting to
explain PA must predict. The purpose of this paper is to determine the
characteristics of PA patches in order to provide better observational
constraints on the suggested mechanisms. All aspects of the temporal behavior
of the individual patches appear to be erratic. Historically, PA has been
defined very loosely and we argue that the use of the term "pulsating" is
inappropriate since our findings and other published results are not regularly
periodic and thus a more appropriate term may be fluctuating aurora. Further,
we find that the observational constraints do not fit well with the flow
cyclotron maser theory, which in particular is suggested to create PA patches.
There is no clear candidate of the suggested mechanisms and drivers to explain
the observational constraints set by the PA patches in a satisfactory manner.
