Re: Velocity estimates

To: Meteor Observers List <MeteorObs@latradedot com>
Subject: Re: Velocity estimates
From: Rainer Arlt <100114.1361@CompuServedot com>
Date: 24 May 96 08:59:20 EDT

The accuracies for velocity estimates derived from a number of experienced
observers is given in the Handbook for Visual Meteor Observers:

angular speed	5	10	15	20	30
error		3	5	6	7	8

Please note that these numbers are not standard deviations (65% confidence), but
include
95% of all estimates. These error limits should be applied (when the speed was
estimated in deg/sec) to shower association (when meteors were plotted).

When I observe together with Jurgen Rendtel, we disagree upon the speed by 5
deg/s or more very seldom. Of course, beginners will not get that accuracy. I
have seen observations with speeds up to 100 deg/s, which are geometrically
impossible. The highest speed for a 72-km/s meteoroid is about 38 deg/s when it
appears in the zenith and perpendicularly to the line of sight (also a geometric
extremum hardly occurring). The majority of meteors is between 5 and 20 deg/s
depending on the shower's v, of course.

Noting the velocity when counting meteors only is in vain, as the information
about the speed is useless with the information on the distance to the radiant
and the height of the meteor above the horizon. Nevertheless, we have to
consider the speed impression for the shower association being done directly
under the sky.

Rainer