(meteorobs) Prediction of Leonids

[Karl Antier]

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