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(meteorobs) Re: Leonids: 1966 rates revised down!
For what it's worth, my reading of the papers, WGN correspondence and
data strongly favours that the peak ZHR was closer to order 100,000
than 10,000. 70,000 sounds plausible. So I'm in accord with Rob.
If we witness a storm in 1998 or 1999 it will help focus our minds on
how we might compute reliable flux densities from video, photographic,
and telescopic observations. I quite appreciate Marco's view that
photographic data have too many free parameters. The vast majority of
the time the observed rates don't justify an estimate of the flux density.
Visual data are abundant, and so over many years we've been able to
derive reasonable empirical correction factors. That's not the case
for other techniques.
The same criticisms can be levelled at telescopic data. There are so
many free parameters. Over and above the usual ones we have the
aperture, magnification (affects apparent brightness for example),
field of view, quality of the optics, whether or not binocular vision
was used, affects of dewing, perception as function of magnified speed
and meteor brightness, distance from the radiant etc. In all these
non-visual methods, the correction for the field of view but finite
path lengths is important. So a knowledge of path lengths versus
magnitude and radiant distance is needed. There have been papers on
this in the BAC (is that in the list of abbreviations Lew?). [Sorry
no references to hand as my meteor reprints are buried in a box at
`home'.]
In the first instance I hope we can at least get a decent profile of
the rates for the given medium using some modest corrections like for
radiant elevation and limiting magnitude.
Malcolm
mjc@tele.imo
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