Re: Radiants

To: meteorobs@latradedot com
Subject: Re: Radiants
From: Mark Davis <MeteorObs@Charlestondot net>
Date: Wed, 08 May 1996 21:23:34 -0400 (EDT)
Date-Warning: Date header was inserted by InfoAvedot net

Lew,

I have often seen meteors that I felt belonged to a shower radiant that at
the time was below the horizon. In my own case, what I do is note the
velocity, path length and path direction and relate it to what I feel the
shower would produce if the radiant was actually above the horizon. Once
I've done that, if I feel confident it was a shower member, I list it as
such on my report. But, all the report forms I fill out, ie. AMS, ALPO, IMO
and NAMN, have room for notes on individual meteors. This is where I make a
note such as "Possible ETA" or "Shower Radiant Below Horizon" or something
similar. This lets everyone know the shower association may be in error.
Note that I look for the same parameters I do for all meteors, no matter
where they are observed. Thus I feel as a person becomes more experienced at
observing, their ability to correctly associate a meteor with a radiant
below the horizon may also increase. I wouldn't though, base any analysis on
observations such as these. :)

But don't mistake the above as my normal method of observing. In practice,
these types of meteors make up less than 1% of my meteor total for the year.
I always try to plan my observation so the radiant is at least 20 degrees
above the horizon. Very rarely will I observe under any other conditions.

In your case with the Eta Aquarid radiant rising at about 4:30 in the
morning, would you consider doing some earlier observing for sporadics? They
are also in need of many more observations! 

Mark

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