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Perseids 2004

A Strong Perseid Maximum

A splendid first Perseid maximum was well-seen from eastern Europe, among other places, peaking at 20h56m +/- 4 mins UT on August 11-12, despite the low radiant then, as reported in preliminary International Meteor Organization (IMO) e-news bulletins. The Zenithal Hourly Rates (ZHRs) were roughly 180-200 at best, although with fresh data still coming in, these figures may be amended later. This maximum had been predicted by professional meteoricist Esko Lyytinen to be centred near 20h54m UT on August 11, which seems to have been remarkably close to what was observed. Initial video results showed a Perseid primary peak a minute or two after 21h UT, while the early radio results implied a peak in the hour centred on 22h UT, but it will be some weeks yet before the majority of the radio data is available for a full analysis.

Observers reporting this peak to us from Germany and Hungary, have described rates of one to two Perseids a minute, sometimes with long paths streaking across a good proportion of the sky, for all the radiant would barely be considered properly observable ordinarily. The peak timing was rather too early for the UK, so we would probably not have seen as impressive a show, but thanks to the remnants of Hurricane Alex, very few places in Britain seem to have enjoyed clearer skies over the Perseids' best anyway.

After this initial maximum, rates dropped quickly. ZHRs were back below 100 before 22h UT, but rose nicely again by roughly midnight UT on August 11-12, and remained at ~100+ for most of the time after then through to around 17h30m UT on August 12-13. No clearer peak has yet become apparent within that interval, albeit coverage of the second, "traditional", maximum time has been rather poor so far, due around 11h-13h30m UT on August 12. This fell best for regions where there are few observers however, across the northern and eastern Pacific and adjoining coastal regions. The problems in defining the later maximum may also be due to an enhanced background level of Perseid rates on August 11-12 and 12-13 generally. This was suggested as a further possibility in Esko Lyytinen's original prediction.

Several people have reported seeing quite a few Perseid fireballs on nights around and after the maximum, but whether these were genuinely more numerous this summer, only a fuller analysis of a lot more data will show. The Perseids are well-known for producing plenty of bright to fireball-class meteors in most years without any unusual activity.

Report by Alastair McBeath, SPA Meteor Section Director

Added by:  Robin Scagell