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Archive for May, 2010

Perseids-2004

In this post, we review the Perseids activity in 2004. A total of 16536 Perseids is comprised by 1567 individual observing periods as used for the below plot.

A short-lived peak of activity was observed at 20h56m UT +-4 min on August 11, 2004. If we assume a background activity of 80-90 during the peak, we can derive the full width at half maximum (FWHM) to be about 55 minutes (20h25m – 21h20m). Enhanced Perseid ZHRs were observed during the entire nights Aug 11/12 and 12/13.

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Perseids-2002

In this post, we review the Perseids activity in 2002 (2000 and 2001 activity were discussed earlier).

Nearly moon-free conditions permitted numerous valuable observations of the nights around the Perseid maximum. The peak time was 22h30 UT on August 12 if a solar longitude of 140.0 degrees is assumed. This time favored European sites, but large parts of central Europe suffered from clouds and rain around August 12. The maximum of the 2002 Perseids falls near a solar longitude of 140.0 (eq. J2000.0), although the curve actually exhibits a plateau between 139.9 and 140.16 when ZHRs exceeded 80. Peak rates are about ZHR = 90 +-5. This result makes the 2002 Perseids a typical return, and the early peak seen in 1988-1999 does not appear or might at best be the (tiny) enhancement at sol=139.91.

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Perseids-2001

I continue the set of Perseids activity with 2001 shower. The 2001 Perseids occurred under rather poor circumstances. Observers either had to put up with the adverse effects of a Last Quarter Moon or start early, in which case they had to deal with low radiant elevations.

What we can conclude from the table below is that Perseid activity reached a very broad top level with a ZHR around 85 between roughly August 12, 9h UTC and the early UTC hours of August 13. Remember from the previous post that the peak associated with the latest return of parent comet Swift-Tuttle could not beĀ  identified in the 2000 Perseid data. The “first peak” might smoothly flow over into the activity associated with the regular Perseid peak, thus creating a very wide and flat plateau of activity.

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