(meteorobs) Meteor Observations form Northern Nevada on June 22, 2006

[Bias, Peter V]

Hi Karl, Robin, and interested others,

Your question is a good one.  I am guessing that it's a regular old
arithmetic average (rather than a geometric one often used for growth
data) because arithmetic means and geometric means would result in a
fairly similar value anyway if there are plenty of (positive)
observations, with the geometric mean always smaller; because our
magnitude perceptions are insufficient to allow for us to distinguish a
real difference; but, mainly, because geometric means don't work with
negative numbers!

The simple average magnitude is not directly used to determine the
population index (which is a fairly complicated procedure) but it can be
used to estimate what the population index is by the simple rule of
thumb that the population index is the same as the average magnitude.
It isn't, of course, (the actual population index is a non-linear
function of the average magnitude) but it's a reasonable first blush
estimate in the field.  The actual functional relationship is
graphically shown in the IMO Meteor Observer's Handbook in Chapter 7
"Meteor Magnitudes" or in my book in Chapter 8 "Zenithal Hourly Rates
and Stream Density."

Hope this helps.

   Pete Bias
 

> -----Original Message-----
> From: meteorobs-bounces at meteorobs.org [mailto:meteorobs-
> bounces at meteorobs.org] On Behalf Of Karl Antier
> Sent: Friday, June 23, 2006 10:12 AM
> To: Global Meteor Observing Forum
> Subject: Re: (meteorobs) Meteor Observations form Northern Nevada on
June
> 22, 2006
> 
> Hi all !
> 
> I was just wondering something : in many meteor reports, one can read,
> as in yours :
> 
> > Shower -2 -1 0 1 2 3 4 5 Average Magnitude
> >
> > SPO 1 5 5 6 3.06
> 
> But how is this average magnitude calculated ?
> Is it a usual average ?
> As magnitude isn't a linear scale, is there a formula to calculate it
?
> And what are the information on meteor showers that are deduced from
this
> information ? r index ?
> 
> Thanks in advance for your answers !
> Clear skies !
> Karl
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