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Re: (meteorobs) A blank meteor reporting form
George Zay>>Mark,
>Your form looks adequate for the most part, but you might want to
>consider removing the entry for "radiant diameter". It essentially
>has no meaning for a visual observer and may cause confusion as to
>where one can find this information?<<
Lew>>I'd have to disagree with George on this one, y'all: knowing what
criteria the observer is using for their shower determination is
very valuable, I imagine! As has been mentioned on here a while ago,
there are a variety of radiant diameters assumed by different exper-
ienced (and not so experienced) observers for each meteor shower.
The IMO literature (some of it) lists "radiant sizes" (i.e., areas
of the sky which observers should match path orientations against)
as large as 15 degrees for some "loose" or poorly observed showers!
Knowing which criteria an observer chose to use that night might be
very important in calibrating their result later. Or am I off here?<<
I think you are off here Lew. For example, IMO's meteor shower calendar lists
the Orionids as having a radiant of 10 degrees. In actuality the orionid
radiant diameter is 0.84 degrees. Then we have the Leonid radiant listed in
IMO's meteor shower calendar as being 5 degrees. In actuality the Leonid
radiant diameter is 0.32 degrees. Why is one listed at 10 degrees and the
other at 5 degrees? There is no reason for it. Is someone gonna have
difficulty in recognizing one shower as being 5 degrees in diameter and
another the difficulty would warrant it being listed at 10 degrees? The S.
Taurids are listed in IMO's meteor shower calendar as being 10 X 5 degrees
while in actuality it is only 2.20 degrees. The S. Taurids have the largest
radiant diameter that I can find. There is no reason to give a shower radiant
all these varying diameters when they are all essentially small. Again to show
on a report form that a shower has an exaggerated radiant diameter when in
actuality it is much less has no initial useful meaning. The distance a meteor
is from the radiant is still gonna determine approximately how large to
balloon the radiant area to accept it as a shower member.
Orienting a meteor path to an exaggerated radiant diameter when the meteor
appears relatively far from the radiant is acceptable. But arbitrarily giving
a radiant a far different size for no reason without having a meteor a given
distance from the radiant from the beginning is not useful.
George Zay