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(meteorobs) ZHRs
Jim Bedient wrote:
> The IMO is fond of quoting big ZHR numbers, and I worry
> a little about the validity of some of it. I noted on the IMO
> site one observer's numbers from the Geminids, with a
> ZHR computed of 119... with an error of plus or minus 45!
> That would come from a sample size of 7 meteors or less,
> and I wonder about such extreme extrapolation from a
> relatively tiny sample. Now don't get upset, this is not an
> attack on the IMO, just an observation on one data point
> among many with lower errors.
I don't think IMO rates are at the high end (I mean ZHRs all the time, of
course). Just as an example Dutch observers saw significantly higher ZHRs for
the Leonids and Geminids. I don't discuss that --- it's a matter of statistics
and observers' perception characteristics. As to the uncertainty of the ZHR
values: The graphs published on the WWW are in the NEWS section, and they are
published a few days after the event when little data has come in. It is most
natural that they will not be a most reliable profile. Look at the global
analyses in WGN, the journal of IMO, where sets of thousands of meteors are
generally used for ZHR graphs. Did I leave out the standard deviations at ZHRs
somewhen? I think it is given in any of the circulars as well as analyses in
WGN.
Raw data are published every year in a special Report Series containing rate and
magnitude data, but no plotting data. The issue with the 1994 data even
cintained a diskette with 1988-1994 data in a easy-to-process format. Everyone
can benefit from the data colleting done within the IMO. No need to
misunderstand the role of IMO as being the holy meteor organization that tells
the only truth about meteors. It was founded to gather the efforts of the many
national meteor organizations as we face statistical problems in meteor science,
and reliable results can only be obtained by the largest data set possible.
Nobody says, other than IMO organizations are doing silly work---can't we leave
the sand-pit games? So, I consider any of your comments about IMO and related
things as a feedback, mainly on the WWW pages, and will do my very best to
improve things, perhaps by putting the global (reliable) analyses into the Web.
Best wishes, Rainer
-----------------------------------------
Rainer Arlt -- Visual Commission Director
International Meteor Organization
100114.1361@compuserve.com
Home page of IMO: http://www.imodot net
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