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RE: (meteorobs) June Lyrid radiant
Jim,
Radiant diameters are not given anymore as these are dependent on the distance
of the meteor from the radiant. Actual physical radiant diamters are generally
smaller than 5 deg. However, when analysing visual observations we have to
compensate the loss of true shower member due to plotting errors with chance
alignments of sporadics. The larger the radiant, the fewer shower meteors are
lost by plotting errors. But more sporadics will be inolved in the rate. Smaller
radiants have the opposite effect. From experiments with the polotting accurcy
we found the following optimum diameters to be assumed when associating meters
with radiants:
distance of the meteors radiant diamter
15 deg 14 deg
30 17
50 20
70 23
These diamters are valid for minor showers with hourly rates around 5. This
varying diameter may look very sophisticated; it is actually sufficient if you
know what is 10 and 20 deg diameter on your chart and use these fairly large
circles for the shower association depending on the meteor's distance. Nobody is
actually measuring each and every distance and diamter on his charts...
The July Phoenicid radiant is not correct in the drift table. The values given
should be valid for July 10 and July 15 resp.
Rainer