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Re: (meteorobs) Re: Visual magnitude

Hi Lew,

You may want to consult the following article:

Brown, Peter., "On the cause and Nature of Error in Zenithal Hourly Rates",
WGN 18.4,
     August 1990, pp. 141-145.

One of the factors discussed is a personal perception factor (P), which is
applied to the general calculation for ZHr when reducing data from various
observers.

This factor was employed by the eastern Europeans when they used paid teams
of visual observers.  These observers were well seasoned and employed over a
number of years, and by making relative comparisons of the data gathered by
each observerunder identical conditions, these professionals derived a
"personal perception factor" for each observerto be applied to that persons
data during data reduction.  Over the years, these perception factors would
be "recalibrated" to take into account the affects of aging, etc.

With the advent of our now far-flung meteor organizations, it is impractical
to set up the "laboratory" conditions necessary for determining perception
factors for all but a handful of observers, but even that may no longer be
done.  The limiting magnitude correction factor will take some perception
differences into account, and minimum data use standards are set for
observing time, limiting magnitude, zenith angle of the radiant, and %
field-of-view coverage.  Seasoned observers are assumed to have a standard
perception factor (1.0) in other areas.

There is something to be said here for letting new observers build their
observing skills, and thus their perception factor, gradually, and not
overloading them with trying to ascertain and record too many meteor
parameters from the beginning.  Even if the beginner manages to plot a
handful of meteors, his/her perception factor is low, and the data collected
is questionable from the researcher's standpoint.  I prefer the method of
asking new observers to build skills gradually, increasing the amount and
sophistication of their data as experience is gained.  This maximizes the
observers perception factor and data accuracy at each stage in their
progress.  All skills acquired, such as estimating meteor duration, are
still used at the next highest level, with additional skills overlayed on
the old.

Take care, everyone,

Jim Richardson
Graceville, FL
Richardson@DigitalExpdot com