(meteorobs) Re: Asymmetric Geminids

[Robert Lunsford]

Bruce and All,

I did not see an answer to your question so I thought I suggest reading the 
following:

http://comets.amsmeteors.org/meteors/showers/geminidhistory.html

This is from Gary Kronk's book on Comet's and Meteor Showers. I'm not sure 
if this is still the current belief as the Geminid rates were expected to 
fall during the 1990's and into the 21st century. Obviously this is not the 
case as was witnessed this past week.

Clear Skies!

Bob Lunsford


----- Original Message ----- 
From: "Bruce McCurdy" <bmccurdy at telusplanet.net>
To: "Global Meteor Observing Forum" <meteorobs at meteorobs.org>
Sent: Saturday, December 11, 2004 12:25 AM
Subject: (meteorobs) Asymmetric Geminids


>    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