Department of Physics,
University of Illinois, Chicago, IL 60680
Observations have been made
of limiting magnitudes indicating that for small to moderate apertures the
expression M(sub L) = 2.8 X log D + 1.9 X log P + M(sub o), where M(sub o) is a
constant dependent on the observer, is more useful in determining working
limits than is the widely used expression of Dimitroff and Baker.