(meteorobs) Asymmetric Geminids

[Bruce McCurdy]

    Sitting by my computer on a cloudy night, listening to the radio
Geminids coming in at the rate of close to one every two minutes and
spending the down time idly thinking. Look out below.

    In one of several highly informative posts, Norman wrote:

> The twist comes right after the time of peak.  Rates fall very rapidly
> almost right afterwards, taking only a few hours to lose what required
four
> full days to build up.  The activity curve is not symmetrical -- it has a
> disappointing cliff.

    I was shocked by this asymmetry last year to the point that I thought my
radio reception might have been poor on the 15th. The drop-off was very
rapid, and very convincing. Here are my hourly radio rates for the 5-hour
window centred on the radiant transiting the local meridian:

                                    UT                    Avg.
Date       |      07    08    09    10    11  |  HR
===============================
Dec 11   |     33    24    25    32    26   |   28
Dec 12   |     34    41    43    46    34   |   40
Dec 13   |     80    77    74    73    43   |   69
Dec 14   |   111    97  105  119    81   | 103
Dec 15   |     18    26    22    18    28   |   22

    I'll be interested to see if this year's results corroborate this.
Judging from Norman's assertion, they should. I just hope the good reception
keeps up... so far so good.

    Several questions: Is there a physical explanation for the asymmetric
distribution of the meteoroid stream? And Norman, could you comment further
on a previous remark you made about the 'expected decline' of the Geminids
in general? Has the stream somehow rippled through Earth's orbit? Finally,
does Earth itself play a role as a 'shepherd' of meteoroid streams in a
manner analogous to what we see in Saturn's F ring?

    Don't feel obliged to answer them all. regards, Bruce