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Re: (meteorobs) Zenith Attraction, some numbers
me>> These showers were listed
>by IMO as those that have activity high enough to make observing
>efforts worthwhile to retrieve usable scientific data from.<<
lew>>This is not what I understood the purpose of the IMO Working List
to be. I understood from (official) IMO representatives in the past
that the purpose of IMO's Working List of Meteor Showers is to list
all showers which are currently known to be distinguishable from
the "Sporadic Background" by visual plots...<<
Quoting a paragraph from Rainer Arlt's article in WGN for the Aug 1995 issue
that gave explanations for various changes to IMO's current working list of
meteor showers...
"Do not forget that the omission of a shower does not necessarily mean this
radiant does not exist. Rather, visual observations cannot provide us with
reliable information about this meteor stream. They may nevertheless be
interesting for telescopic, photographic, video, or radio observations".
I'm not sure in what way, what you are saying, is any different than what I
said? It seems to me that Rainer is saying basically the same thing I said in
different words?
lew>>This isn't to say there may not be periodic showers, i.e., showers
subject to outbursts above the Sporadic Background, which will not
be worth observing by visual means. (An excellent example of this
would be the off-again, on-again June Bootids, which were removed
from the Working List a number of years ago, only to be revived by
an unexpected JBO outburst in 1998!)<<
No it doesn't...but if activity is obviously periodic and stands out when it
is active, it is on IMO's working list...such as the Draconids. If anything
unusual shows up outside of the working list, no doubt it will be
noted....even if listed as sporadics, the plots will show up in the analyses
as they are entered into rainer's computer. The working list is meant to
streamline efforts for the visual observer and not bog them down with
hundreds or even thousands of "showers" from the past that has shown no or
marginal activity over many years. It is a "working list" from which a visual
observers' efforts can provide some useful information. Not a list of every
radiant that has come and gone in the past. Shower's appear and disappear for
many years. Some don't come back. After many years of inactivity, until they
show some signs of obvious life, there is no need to get worked up about
them.
lew>> Nor is it intended to preclude
OTHER observational methods, such as telescopic plotting or video,
from being used on non-Working List showers.<<
Correct, but the Working List of Visual Meteor Showers is just that....for
observers using just the eye ball to gather data. If someone wants to gather
useful information, they will have to rely on other means beyond eyeball
observations with more advanced equipment.
lew>>One thing the Working
List *is* intended to do, especially for newcomers to plotting, is
provide a limited catalog of well-established showers for us to use
in our own plotting analyses - but that's really it's ONLY purpose.<<
It provides a limited catalog of well established showers from which visual
observations can provide useable information on whether one is doing the
Counting method or Plotting method. If it's not on the list, it's most likely
a shower from which nothing worthwhile can be derived thru visual means
unless some new activity starts up again.
lew>>In other words, the Working List is the RESULT of doing statistical
analysis on observed data. It is NOT intended to be a FILTER to be
pre-applied to that data beforehand! Let's always try to keep the
("double-blind") nature of scientific observation in mind, folks!<<
Yes the list is a result of significant statistical analysis from observed
data. But it is also a filter. If you have a meteor plotted that lines up
with a known shower radiant and it just happens to line up on a radiant
belonging to somebody's "Wish list" due to very low activity, you should list
it as a shower member of the most active shower that is occuring...assuming
alignment and path length is proper as well. If you are plotting, anything
unusual will stand out during analysis. You won't miss out on anything. If a
non-IMO working list radiant kicks in, you will have other clues to indicate
something to perk up about...namely other meteors in significant numbers
should also end up being plotted that will not align onto working list
radiants.
GeoZay
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