(meteorobs) Delayed Perseid Peak?

Wes Stone howard048 at centurytel.net
Sat Aug 16 16:45:59 EDT 2008


Looking at the on-the-fly ZHR graph on the IMO page, one can see the broad 
peak that Chris is referring to on the morning of August 12 for North 
American observers. The peak ZHR is around 85. But of course the most 
obvious feature is the huge peak early on the morning of August 13 for 
European observers. This lasts just a few hours at most, and by the time the 
radiant is in a good position for the Western US on the morning of the 13th 
the rates are back down to where they should be on the day after the peak 
(and this would account for the rate profile Chris captured on his video).

I'm sure these rates will be refined as more data is added/verified, but 
here are a few snapshot numbers from the automated page at 
http://www.imo.net/live/perseids2008/:

August 12, 2:41 UT: ZHR 70
August 12, 9:24 UT: ZHR 83
August 12, 16:56 UT: ZHR 71
August 13, 2:16 UT: ZHR 137
August 13, 6:59 UT: ZHR 57

That looks like an unexpected outburst to me, superimposed on the broad 
"traditional" maximum. But we'll have to see what formal analysis comes up 
with.

--
Wes Stone
Chiloquin, OR
http://skytour.homestead.com

----- Original Message ----- 
From: "Chris Peterson" <clp at alumni.caltech.edu>
To: "Global Meteor Observing Forum" <meteorobs at meteorobs.org>
Sent: Friday, August 15, 2008 12:03 PM
Subject: Re: (meteorobs) Delayed Perseid Peak?


> Anthony-
>
> I didn't observe a later peak. My video data shows a broad peak on 8/12
> around UT 10:00, when I was recording over 50 meteors per hour brighter 
> than
> mag 1. On 8/13 I had a fairly uniform rate, increasing slightly over the
> evening because of the radiant position. Except for a very brief spike at 
> UT
> 10:15 (10 events in 15 minutes), the general level in the early morning
> hours was around 20 meteors per hour.
>
> While the brightest fireballs I recorded were on 8/13, the fireball rate
> wasn't substantially different between the two nights: on 8/12 I recorded
> 152 meteors, of which 23 were brighter than mag -4 (15%); on 8/13 I 
> recorded
> 117 meteors, of which 12 were brighter than mag -4 (10%).
>
> While solidly locating the peak of such a broad shower is tricky, I'd say 
> my
> data puts it within an hour or two of the predicted time. My 8/12 data 
> seems
> to show more structure in the frequency: the rate rose and fell with about 
> a
> 30-minute cycle. On 8/13, the rate was much more uniform.
>
> Chris
>
> *****************************************
> Chris L Peterson
> Cloudbait Observatory
> http://www.cloudbait.com
>
>
> ----- Original Message ----- 
> From: <GLDSKTR at aol.com>
> To: <meteorobs at meteorobs.org>
> Sent: Friday, August 15, 2008 5:16 AM
> Subject: (meteorobs) Delayed Perseid Peak?
>
>
>> It seems that the Perseid peak arrived a day LATER than originally
>> calculated, according to most reports. Many more fireballs reported also.
>> I  noticed
>> an increase in fireballs as the morning of 8/12 approached.
>> Could this have been just a total miscalculation, or a possible part  of
>> the
>> stream that just dispersed over time, and was a complete  surprise?
>
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