(meteorobs) What is the FM(FMD)

[Mikhail Maslov]

No, this parameter primarily shows the strength of the outburst, not
its duration. Expected ZHR is in direct proportion to absolute value
of fM(fMD).
I calculate fM(fMD) basing on the difference between moments of
passing their points of minimal distances to the Earth's orbit (MD) of two
particles with ejection velocities differing by one computation step (0.1 m/c,
0.01 m/s, for example, 4.2 and 4.3 m/s). I said basing as this
temporal difference is the main factor for fM(fMD), but also such
values as difference between rD-rE for these particles and difference
between solar longitudes of their MD points are taken into account.
Normally their contributions are neglibly small, but under some
conditions they can become more substantial.

Speaking of negative fM(fMD) values - they come when the trail
is reversed, i.e. particles with higher ejection velocities pass their
MD points earlier than particles with lower ejection velocities. In
this case the temporal difference for, say, particles with ejection
velocities of 4.2 and 4.3 m/s     is negative, so the whole fM(fMD) value
turns to be negative.

Don't hesitate to ask if you feel something is still not fully understood.

Best regards, Mikhail.



Y> Thank you for your answer.But I did not understand it very clearly.In this webside,I read that:
 
Y> http://feraj.narod.ru/Radiants/Predictions/1901-2100eng/Leonids-introeng.html
Y> fM(fMD) - the characteristic of longitudinal density of the trail, it is derived from the time interval between passages of minimal distance to the Earth's orbit by particles with different
Y> ejection velocities
 
Y> Is it show that how long  the shower will last? If so,Why do some FM(FMD) is a negative?
 
Y> Best wishes,Yi Cao
 
 
>> Date: Mon, 26 Oct 2009 21:27:37 +0600
>> From: ast3 at ngs.ru
>> To: meteorobs at meteorobs.org
>> Subject: Re: (meteorobs) What is the meaning of FM(FMD)
>> 
>> It is a parameter showing the density of meteor trail. For example,
>> FM(FMD) for 1 revolution Leonid trail is ~1.
>> 
>> Best regards, Mikhail
>> 
>> Y> I have read this prediction about LEO meteor shower,but I do not understand the meaning of FM(FMD).Dose anybody know it?I very much hope that an answer.
>> 
>>  --Yi Cao
                                          
Y> _________________________________________________________________
Y> 全新 Windows 7：寻找最适合您的 PC。了解详情。
Y> http://www.microsoft.com/china/windows/buy/ 
Y> _______________________________________________
Y> Mailing list meteorobs: meteorobs at meteorobs.org
Y> To UNSUBSCRIBE, email: owner-meteorobs at meteorobs.org
Y> http://lists.meteorobs.org/mailman/listinfo/meteorobs