  Frank and Sigwarth (2001,JGRSP,106,A3,3665; FS) report on an optical search
for small comets in which they report detection of nine faint trails. FS claim
that these trails are produced by low-mass, low-albedo ob-jects whose inferred
number density is consistent with that predicted by the small comet hypothesis.
The images used for the search were the same as those obtained in a previous
unsuccessful optical search for small comets reported by Mutel and Fix (2000,
JGRSP,105,24907; MF). The results of these two independent analyses of the same
image dataset are not formally in disagreement, since all detections reported
by FS are fainter than the minimum detectable magnitude limit (16.5) determined
by MF. However, since the conclusions are quite different, we have
independently re-analyzed the original search images for evidence of the faint
detections reported by FS. In particular, we have carefully examined whether
the three putative trails whose positions are available satisfy several
necessary criteria for a candidate grouping of excess-count pixels to be caused
by a celestial object. While we have not evaluated the formal statistical
significance of faint detections, all three claimed detections fail one or more
independent criteria required for a valid detection. In addition, both the
level and shape of the claimed integral detection rate versus magnitude are in
strong disagreement with the inte-gral number density of the small comets
hypothesis. We conclude that unless the remaining claimed detections can prove
otherwise, the lack of detections after "careful examination" of the 1,500
search images described in FS provides the most compelling evidence yet
published against the small comet hypothesis.
