  Transient lunar phenomena (TLPs) have been reported for centuries, but their
nature is largely unsettled. A review of TLP reports shows regularities in the
observations; a key question is whether this structure is imposed by human
observer effects, terrestrial atmospheric effects or processes tied to the
lunar surface. I interrogate an extensive TLP catalog to determine if human
factors determine the distribution of TLP reports. I divide the sample
according to variables which should produce varying results if determining
factors involve humans e.g., historical epoch or geographical location of the
observer, not reflecting phenomena tied to the lunar surface. Regardless of how
we split the ample, the results are similar: ~50% of the reports involve crater
Aristarchus nd vicinity, ~16% from Plato, ~6% from other recent, major impacts,
plus a few at Grimaldi. Mare Crisium produces a robust signal for three of five
averages of up to 7% of the reports (however, Crisium is an extended feature).
The consistency in TLP report counts for specific features indicates that >~80%
of reports are consistent with being real (perhaps excepting Crisium). Some
commonly reported sites disappear from the robust averages, including
Alphonsus, Ross D and Gassendi. TLP reports supporting these sites originate
almost entirely after year 1955, when TLPs became more popular targets of
observation and many more (and inexperienced) observers searched for TLPs. In a
companion paper, we compare the spatial distribution of robust TLP sites of
transient outgassing (seen on Apollo and Lunar Prospector). To a high
confidence against the random hypothesis, robust TLP sites and those of lunar
outgassing correlate strongly, further arguing for the reality of TLPs.
[Abstract abridged.]

Astrophysics