(meteorobs) Re^2: Prediction of Leonids

[Mikiya Sato]

Hello all,

>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 ?

The value of dR is the distance from the trail to the Earth orbit 
at the node point of trail on ecliptic plane (Earth orbital plane).

> And what for fM ? Is it an
>index of the possible activity ? In that case, how is that index calculated
>?

I knew the value of "fM" at the paper by McNaught and Asher.
The value of "fM" is the scale of the extended degree of a trail.
Since I am poor at explaining in English, please look at following figure
(drown by me).

http://kaicho.pobox.ne.jp/tenshow/meteor/55p2004/fm.gif

>Second, what do middle and low scale activities really mean ? ZHR = 50 for
>middle activity ? More ? Less ? And for low activity ? ZHR < 10 ?

Although "Middle scale" is smaller than the scale of main meteor showers
(example the peak of Perseids or Geminids), it is an active scale.
It means that ZHR is around 20 to 50, if a numerical value dares be shown.
"Low level (or small peak)" is not so active, but it is the scale which
 may be able to observe its peak. 
It means that ZHR is less than about 20 (if....).

But I am sorry, I cannot take out a concrete numerical value since I have 
not been studying it in detail.
I think that the prediction of the appearance below such middle-scale
is very difficult, rather than a large-scale appearance (such as
 great shower), in the case of Leonids.
Probably, about various cases, I have to study more.

Best wishes,

Mikiya Sato