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Reporting on the Leonids - PART II
by the IMO
From: meteors
To: NAMN
Subject: Fw: Leonid reports, Part 2
Date: Mon, 11 Nov 2002 19:20:51 -0500
Reporting on the Leonids - PART II
==================================
This is the second of my messages about Leonid reporting.
The observational data will be more precise if meteors
not belonging to the Leonid radiant are sorted out. We call
these 'non-LEO'. Here is an example of the modified report:
==================
Observer: Tom KING
Place: Huntington, NY (Lat 40.8 N, long 73.4 W)
Time: 9:45-10:46, 19 Nov 2002 UT. [UNIVERSAL TIME = EST+5]
Effective time: 100% (no time lost to looking away or breaks)
Limiting mag.: +5.0 [measured by counting stars]
Field obstructions: none.
Direction faced: Taurus
ONE MINUTE COUNTS STARTING 09:45 UT
TIME LEO non-LEO
09:45 23 0
09:46 17 0
09:47 18 1 (10% cloud)
09:48 15 0 (30% cloud)
09:49 BREAK
09:55 18 0
09:56 24 1
09:57 22 0
...
==================
Leonid association
------------------
The radiant of the Leonids is the point from where all the
shower members seem to emanate. If you extend the meteor's
path backwards, and the extension meets the radiant point
at RA = 10h20m, DEC = +22, it was most likely a Leonid.
Most Leonids are very fast; near the radiant, however, they
can appear fairly slow and short. Meteors close to the radiant
must be short. A meteor of 10 degrees length at 5 degrees
distance from radiant is not a Leonid.
Meteors moving _towards_ the radiant, are not Leonid members.
At rates of say 20 meteors a minute, you will feel unable to
check Leonid association. It is entirely adequate to drop the
LEO/non-LEO discrimination then.
Difficult meteors
-----------------
You will see quite a few meteors at the edge of your field
of view. If you are not sure whether or not this was a Leonid,
count it as a Leonid. The reason is, that it is statistically
the more likely case that you saw a Leonid, because their
activity is higher than the non-LEO activity.
The non-LEO activity will be roughly 0-3 meteors in 10 minutes
given the lunar conditions this year. While observing, if you
notice that you regularly log more than this, you should be
less restrictive with Leonid association.
Send data from...
North America to .......................... namn@0atmob.org
other locations to ........................ visual@imo.net
Coming soon: Part III, Recording magnitudes
Best wishes,
Rainer Arlt
Rainer Arlt -- Astrophysikalisches Institut Potsdam -- www.aip.de
Visual Commission - International Meteor Organization -- www.imo.net
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