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Re: (meteorobs) Leonids 2000-2006



Dear John:
	In 1998 and 1999 our planet was yet far from the region
of the "dust trail" studied by Sykes et al. (1990) and  Sykes
and Walker (1992) (both articles published in Icarus).  According 
to these researchers, dust trails contains a
larger fraction of particles with diameters of ~1 cm (+- a 
factor of 2).  The Isolines Method (IM) performed an independent
calculation, and also found particles of ~0.5 cms or so.
When two independent methods give the same result, there is
some scientific basis to believe the result.
	Our planet is going to enter this region starting in the
year 2000.  The specific prediction is that the number of large
particles (brighter meteors) should increase in the coming 
years.   I have not performed the calculation, but somebody can
surely tell us the brightness of a meteor produced by a particle
of 0.25 to 2 cms.
	I hope this clarifies the situation.

Ignacio Ferrin,
Center for Theoretical Astrophysics,
University of the Andes,
Merida, VENEZUELA.
===========================================================================

On Fri, 11 Feb 2000 newtonj@ttc.com wrote:

> Hi all,
> 
>      A question comes to mind..... Immediately following the table, it is
> mentioned    "   It can be
> seen that the Isolines Method (IM) gave the best prediction, suggesting that
> it has some predictive power.  In fact IM makes an additional prediction not
> mentioned elsewhere: beginning in the year 2000, and up perhaps to the year
> 2006, the Earth will enter a region with a larger proportion of large
> particles.  These should produce brighter meteors."
> 
> Did the IM predict or match well with the "fireball storm" of the 
'98 Leonids?
> 
> John N.
> 
> 
> 
> 
> 
> 
> Ignacio Ramon Ferrin Vasquez <ferrin@ciens.ula.ve> on 02/09/2000 10:22:52 AM
> 
> Please respond to meteorobs@jovian.com
> 
> To:   meteorobs@jovian.com
> cc:
> Subject:  (meteorobs) Leonids 2000-2006
> 
> 
> 
> 
>                                         Merida, February 7th, 2000
> Letter To Meteorobs.
> 
>         It is now clear that Asher and McNaught (1999), predicted the
> time  of the Leonids meteor shower with an error of only 2 minutes, a very
> small value.
>         However it should be remembered, that just as in any x-y plot,
> a prediction of a meteor shower involves two quantities, intensity and
> time.  The time prediction was excelent.  Let us compare the predicted
> intensities (ZHR) compiled in the table below.
> ---------------------------------------------------------------------
> Authors \ Year                  1999    2000    2001    2002    2006
> ---------------------------------------------------------------------
> McNaught and Asher (1999)        500    20?to   15000   25000   100
> (Letter to IMO, Nov. 9th)      +1500    30?
>                                 -300
> ---------------------------------------------------------------------
> Rao (Letter to Meteorbs,        2000to
> Oct. 1999)                      6000
> ---------------------------------------------------------------------
> Isolines Method (Ferrin, A&A,   3500    5000to  400     100     20
> v. 238, p. 295, 1999)         +-1000    20000
> ---------------------------------------------------------------------
> OBSERVED (Arlt et al.,          3700
> WGN, 27:6, p. 286, Dec. 1999) +-100
> ---------------------------------------------------------------------
>         It can be seen that the Isolines Method (IM) gave the best
> prediction, suggesting that it has some predictive power.  In fact IM
> makes
> an additional prediction not mentioned elsewhere: beguinning in the year
> 2000, and up perhaps to the year 2006, the Earth will enter a region with
> a larger proportion of large particles.  These should produce brighter
> meteors.  It will also reflect on the "r" value of the distribution.
>         The situation becomes rather interesting for the coming years.
> While Asher and McNaught predict a very poor shower for 2000, with an
> intensity of 20 to 30, IM predicts a very intense shower of 5000 < ZHR
> < 20000, better than in 1999.  I have recently revised these calculations,
> with the result that the year 2000 rate may be even higher that
> 20.000.  The only difficulty in confirming this activity is that the moon
> is going to interfere with observations.
>         For the year 2001 and 2002, the Isolines Method predicts very
> minor
> showers, diminishing with the year.  On the contrary Asher and McNaught
> predict an intense shower in 2001 and even more intense in 2002, a very
> different result.
>         This is good for science, because we will soon know which one of
> two methods have the best predictive power.  It is also good for
> everybody,
> because both predictions predict intense showers in the coming years!
>         The best is yet to come!
> +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
> ~
> 
> 
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> 
> 
> 
> 
> 
> 

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