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(meteorobs) RE: meteorobs-digest V1 #125
Lew wrote:
>But is this straight-line path also an artifact of a meteoroid's entry into
the
>atmosphere? And are TWO angular velocities actually required to
calculate the
>geocentric velocity? It seems like once a straight path in the
atmosphere is
>found, EITHER station's apparent angular velocity (or anyone else on
earth's for
>that matter) should be enough to derive the true geocentric velocity.
Oder? ;>
Yes, this is right. A single photograph determines a plane through the
meteor's trajectory and the observation point. Two photographs
determine a line segment through the atmospere (the trajectory of the
meteor). One angular velocity is enough then to determine the real
velocity of the meteor.
Still, a second measurement of the angular velocity is very valuable
because it gives you a check on the validity of the results. E.g. when the
appearance time of the meteor is not right, the calculated trajectory
may be shifted from the true position and come closer to one station
and move away from the other. Than the first station would see a too
small velocity (= range times angular velocity) and the other a too high
velocity.
>[PS: I know all of this can probably be found in the IMO Photographic
Handbook,
>but please help me save book money by answering the question here
instead! :)]
But maybe you can save a lot of effort by obtaining this valuable
information!
>Thanks in advance for hard answers to goofy questions!
>Lew
>
You're welcome,
Marc de Lignie