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Re: (meteorobs) Recording storms

On Tue, 21 Dec 1999, Asaf Shtull-Trauring wrote:
> Well, there was a certain point in the meteor shower,
> where we saw lke 4 meteors per second, and once or
> twice even more than 8! Who has time for taperecorders
> when viewing such an incredible thing!

Observers in Jordan and Egypt who used taperecorders did indeed have some
difficulty, and it is an important point to have some idea of where visual
observations fail to keep an accurate count of numbers.  Simulations using
MetSim (if that is the name of Sirko's program) are one approach.  Another
is the subjective experience from this year's Leonids.  My own experience
is typical of that of others I spoke to, so I'll describe how I coped with
the high rates, although I still have to go thru my tape again to get the
exact times and rates at which I noted the various transitions.

When noting magnitudes, at about 30 Leonids/minute there was often
insufficient time to consciously estimate the magnitude and it became
necessary to "force" a guesstimate as soon as possible to prevent an
ensuing "pile up" of unrecorded observations.

Eventually, the rate got just too high, and to prevent loss of numbers, I
just had to abandon magnitudes and said "now" on the appearance of a
Leonid.  (I've heard Bob or someone else did exactly the same, although a
hand beeper would have been better I think.)  For the most part this was
still okay at around 60/minute, but by that time the point had been passed
when EVERY meteor could be counted that way, and great mental
concentration was required to estimate total numbers in short periods when
several occurred.  I quickly learned that this had to be done without
hesitation, as every instant of delay just compounded the problem.
Numerous times during maximum, I'd exclaim "4 then, 3 more" etc, but these
seemed to be correct estimates and only on a few occasions was I sure I'd
miscounted.  These occasions were always undercounting, and the
uncertainty in my estimates at maximum were in my assessment of how many I
guessed were missed.  However at the rate of around 60/minute, this
represented only maybe 2 or 3 Leonids during the minute and my feeling was
that these estimates were reasonable, meaning the number counted was
probably only in error by 1 or 2% over what I actually saw.  The greatest
number I saw instantaneously was 7, four below, three above the radiant
showing an impressive differential acceleration from the radiant.

Several times approaching the peak, I consciously noted that I was
close to my ability to cope with the rates, or rather the periods of
statistical fluctuation of highest rates.  Close to maximum I noted that if
the rates increased I'd certainly start to lose count, but then the rates
obliged by beginning to fall!

Others I spoke to felt they had coped reasonably well (i.e. insignificant
counting error) at rates of around 60/minute, but I feel counting would
break down noticeably at rates of around 100/minute.  The question then
would be just how reliably the guesses would represent the total?

Cheers, Rob



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