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Re: (meteorobs) point meteors and Binocs

Sorry I'd just left for a conference when this message was sent.  It was
only this weekend that I was able to go through my entire email inbox.

> Tom Fleming asks:
> >Is the radiant the best place to attempt binocular
> >observations of meteors during a shower?

No.  Rates would be very low at the radiant.

> Actually, Tom, I know of at least one researcher who would be *very glad*, if
> you were to try doing Telescopic (includes binoculars) Meteor plotting during
> the Leonid peak night! :)  Malcolm Currie is also probably the best person to
> answer Tom's question about plotting chart positions...

The best place is a tradeoff between observing a larger cross-section of
atmosphere, the apparent angular speed, and determining the radiant
properties.  The last being one of the goals of telescopic observing.

If you go too far from the radiant, any plotting errors are magnified
when extrapolated back to the radiant.  Also as the angular speed
increases the meteors are harder to detect, and the speed estimates
become less reliable.  The speed (given a known shower velocity) defines
the radiant distance from where the meteor is seen.

If meteors are seen as lines, the effective field of view is increased.
You can see meteors which start beyond your field and end within it,
and those which start in your field but leave.  Point meteors can only
be seen if they appear within the field of view.  Also there are lots
of flashing satellites up there, which might easily be confused with a
point meteor.  So observing at the radiant isn't a good idea.

For shower like the Leonids whose meteors are fast, I observe about
10-15 degrees from the radiant.  For medium-speed showers like the
Geminids, about 15-25 degrees away.  For the slowest it's 20-35 degrees.
There are other factors like selecting suitable fields for plotting.
It's not an exact science.

Malcolm Currie

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