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Re: (meteorobs) Seeing the Geminids this year



OOops! You are right Lew, I mistakenly thought Las Vegas was 
GMT-7 when its really in Pacific time, GMT-8 ! So, basically just 
subtract 1 hour from all of my "predictions" to get :

1.) 1:40am night of Dec 13/14 (+/- a few hours)
2.) 7:30pm - 8:30pm night of Dec 14/15
3.) 1:40am night of Dec 14/15 (+/- a few hours)
4.) 6:15pm - 7:15pm night of Dec 13/14
5.) 1:40am night of Dec 12/13 (+/- a few hours)

And, yes the 1:40am is based simply on radiant culmination. 
However, I think the "window" just before moonrise on Dec 14/15 
may turn out well. The mean radiant elevation during that hour is 
24° (at Las Vegas) and using the formula 1/Sin(elev) gives a rate 
reduction to about 40% of the rate if the radiant were at the Zenith. 
This will be fully compensated by lack of moonlight. (Its also a 
much better time of night for most folks in the middle of a work 
week! )

Note: The exact timing of this window will vary substantially 
depending on your geographic location. For example:

Miami, FL 8:20 - 9:20 pm
New York City  7:25 - 8:25 pm
San Francisco  7:50 - 8:50 pm

If anyone wants the exact times for their location ,just send me a 
email privately.

Cheers!
Mike.

 
On 6 Dec 2000, at 10:57, Lew Gramer wrote:
 
> Mike, you make clear your reasons for the early evening times you mention
> (times of moonrise, mainly). Although radiant elevation really does have
> an unbelievable influence on observed rates (see IMO website or Handbook),
> and the GEM radiant will be very low indeed during those hours, I have to
> agree that the PROCESS of observing is more pleasant without the moon. :)
> 
> However, what are the reasons behind your other predicted times? I haven't
> heard any such detailed predictions of peak times for the GEMs - especially
> because, as you say, the peak times are generally so broad for this shower.
> Are these simply radiant culmination times? I doubted that, as they are an
> hour too late for that. Just curious, thanks for any info.
> 
> Clear skies!
> Lew Gramer


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