[Prev][Next][Index][Thread]
Re: (meteorobs) meteor duration estimates
> Meteor durations can only be judged by how they appeared. This is the sense
> of short intervals that you only develop through practice. I trained by
> visualizing meteors while watching a second hand on a watch. Jim's
> technique sounds good, too. George, Jim didn't mean using the stopwatch in
> actual timings, just developing his sense of timing.
I agree with Jim and Norman, that estimating the duration of a meteor is
not that a challange. After all, you also have to estimate the
brightness of a meteor at one instant, so why shouldn't you be able to
give a good estimate of it's duration? Once you have observed a collection
of shooting stars you should be able to give it's duration with an
accuracy of 0.2s or so.
Good questions, what those estimates are good for. It might help
you for the determination of the meteor's angular velocity. You imagine
how long the meteor would have traveled among the stars if it had lasted 1
second, and then you determine that distance. I have no idea what else the
duration could be good for. By the way, I normally record only unusual
long lasting meteor, say larger than 0.5s or so.
Last but not least there is a fine method of tunig your time estimates: By
watching a video tape from a wide angle video system! Such tapes look very
similar to what you see with your naked eyes in the sky. After you have
estimated a meteor's duration you can replay the tape in slow motion and
count the number of frames the meteor was visible on. From the hundreds of
video meteors of MOVIE I have measured so far I found, that most meteor
last between 0.2 and 0.3 seconds.
Cheers, Sirko
**************************************************************************
* Sirko Molau * __ *
* Str.246 Nr.16 * " 2B v 2B " *
* D-13086 Berlin * *
* smo@informatik.tu-chemnitzdot de * Shakespeare *
* http://www.tu-chemnitzdot de/~smo * *
**************************************************************************
References: