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Re: (meteorobs) Notification of possible showers

Not sure which of the threads to reply to on this subject.  I'm
somewhat schizoid on this topic as it is.  You see I agree with both
Mike and Bob.  There isn't a clear-cut answer.  I've used both
approaches and judged on a case-by-case basis.

From the telescopic perspective, there are so few observers, having a
carrot to tempt people out while there is no major-shower activity is
an important consideration.  There again for some suspected radiants
I like to see confirmed or refuted, I've given the time and approximate
position, say the general region or constellation.  By adopting a
suitable pattern of field centres, it is possible to still record any
meteors from these putative showers, without giving the game away.
That way we can obtain plots because people are more motivated to go
out, but they still observe reasonably objectively.  I've not tried
the imaginary shower to get people out, where they might actually
find a real shower, but there's a thought.  (-:

At some point you write up your findings, let's say in WGN or on a Web
site.  Thereafter, it's in the public domain.  The genie is out of the
bottle.  Some observers will read your report and take it into
account.  So should one wait until confirmation before publication?  In
the visual field I'd lean towards a yes answer.  For telescopic, I'd
veer the opposite way.  Publication promotes interest in telescopic
observing.  Also the bias is reduced because of the restricted field,
and rotation and reflection of the field in refractors.  There are so
many more visual observers who can confirm your naked-eye report, and
these days it will be rare for you to be the sole witness to a
significant visual shower. 

When dealing with minor showers and hunting for weak radiants, we
really have to plot the meteors, and use statistical analyses to sift
the real showers from the sporadic noise.  Claims for showers with
ZHRs <3 are hard to justify without spatial information.  I do like
the "see it, plot it" approach, and only do shower assignment after
the watch is over.  Video does have an important place, but as Marco
said, it's not final arbiter.  Its one of the complimentary techniques
we can bring to bear.  Video's perception (to bring in yet another
interesting recent thread) is different.

We mustn't forget there is bias in shower assignments for major
showers.  Inexperienced observers do tend to lump in sporadics to
their shower totals.  Rates are too high to plot at such times. That
does mean the bias is a smaller fraction of the ZHR than for minor
showers.  The bias is further mitigated by averaging because the peak
of the Perseids, say, will be watched by many (experienced) observers
too.  The main result is a good approximation to the rate curve.

For a minor shower, or possible shower where we expect weak rates at
best, we do have to be cautious not prejudice our plots.  The odd
sporadic meteor bent to fit in the shower's bin can alter the ZHR by a
large fraction.  That's a hazard of instant shower assignment.  

My approach is one of caution where a possible radiant is expected
only to yield weak activity.  Where we expect stronger or short-lived
activity, like the alpha-Monocerotids, giving full details prior is
correct in my view.

Malcolm

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