(meteorobs) Prediction of Leonids

[Bias, Peter V]

Hi Karl and everyone,

  I emailed Mikiya Sato and asked the very same question about fM.  This is what he answered (I hope he doesn't mind!):

>A value of "fM" is one scale of the distribution of trail.
>A density of the trail after the usual one revolution is set to 1.
>When there is no perturbation, the value is set to 1/n after n-revolution.

>But some perturbations usually acts on a trail, "fM" is larger than 1/n 
>or smaller than 1/n. When "fM" is larger, the trail may be thicker.

>So, if "fM" of 1965 is 1.15, the trail is a little thicker than usual.
>(But true value is 0.94 by recalculation.)

>Moreover, these values can compare in the same discharge speed.
>Exact density is not expressed when discharge speed differs greatly.

>In case of trail from 1965, "fM" is very large (about 1), but discharge 
>speed is very fast (about 120 [m/s]). So, probably, actual trail density 
>will be very small.

>For example, the discharge speed of 1333 is 14.27[m/s] and that of 1167 
>is 13.10[m/s], these are the similar values.
>And "fM" of 1167 is 0.0048, smaller than one of 1333 which is 0.022.
>Therefore, probably, the number of meteor of 1167 was fewer than 1333.
>(In fact, it is necessary to take approach distance into consideration.)

  Maybe this will help, but this still seems somewhat unclear to me.  Wouldn't density after one revolution be different for every meteoroid stream from any comet and even for every "discharge" for the same comet had it noticeably changed its orbit?   

  Can anyone help Karl and me (and probably many others)?

-----Original Message-----
From: meteorobs-bounces at meteorobs.org
[mailto:meteorobs-bounces at meteorobs.org]On Behalf Of Karl Antier
Sent: Friday, October 29, 2004 4:50 AM
To: Global Meteor Observing Forum
Subject: Re: (meteorobs) Prediction of Leonids


Hello all meteor observers !

Just a few questions about these predictions of Leonid peaks for this year,
mainly about the different figures in this table :

> Trail Time (UT)     dR(AU)   fM      Expected peak level
> 1733  Nov.19 21:26  -0.0023  0.10    Middle scale peak
> 1333  Nov.19  6:39  +0.0018  0.022   Low level peak
> 1135  Nov.21  8:21  +0.0006  0.0039  Low level peak?

Sorry if these questions seem for you to be evident, but they don't sound
like that to me... If someone couls help me...
First, what do dR and fM refer to ? Does dR refer to the distance from the
trail to the orbit of the Earth at this date ? And what for fM ? Is it an
index of the possible activity ? In that case, how is that index calculated
?
Second, what do middle and low scale activities really mean ? ZHR = 50 for
middle activity ? More ? Less ? And for low activity ? ZHR < 10 ?

Thanks in advance for your answers !

Clear skies to all !
Karl

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