The Perseid maximum is due between 11h30m-14h00m UT on August 12 this year, and should produce typical healthy Perseid numbers. Zenithal Hourly Rates (ZHRs) thus should be around 80-100. Though this timing is obviously poor for British visual observers, the peak should still remain observable by radio methods even here (as long as interference permits, at least). However, Finnish meteor expert Esko Lyytinen has suggested the Earth may encounter a denser meteoroid trail for perhaps an hour or so centred on 05h26m UT that morning, producing an additional stronger maximum ahead of what would be usually the main peak, much as was seen back in 1991-98 and again in 2004. Esko suggested ZHRs could reach 100-300, perhaps higher, and there seems a good prospect for brighter than normal Perseid meteors to be involved. This timing too is unhelpful for British visual observers of course, but we should catch part of the rising activity this way later in the night of August 11-12, with luck, and again radio observers should be able to cover this potential peak interval from here. Meteor rates will likely remain most acceptable by August 12-13 too, if doubtless below their best. The Moon is waxing gibbous, near its lowest in the sky, and will set around midnight UT for most UK sites on each night, leaving much of the second half of the night free for dark-sky watching. This is so as the shower's radiant first reaches a useful elevation to the northeast by about 22h UT, and improves all night after then, to culminate well after sunrise, around 06h. Perseids are swift, often bright, and commonly trained meteors. The shower lasts from July 17 to August 24 in most years, producing very much lower rates away from the peak.
For more information and a Perseid radiant chart, see the August activity webpage at: http://www.popastro.com/sections/meteor ... ug2008.htm
If you're able to observe during the Perseids and would like to contribute full information to the SPA Meteor Section, there is advice on how to do so and an electronic report form available via links on the homepage at: http://www.popastro.com/sections/meteor.htm
. If you're planning a less formal observing session or two during the shower, that information can still be useful, providing you send me the following data:
1) Your name and observing site (place name and county name for UK locations; place name and geographic coordinates for anywhere else).
2) The date of your watch (ALWAYS use the double-date over midnight to avoid any ambiguity) and the times you watched between, stating clearly if this was in clock time, BST, or GMT/UT. If you took breaks when you were not constantly watching the sky for meteors, please state the total time you WERE watching the sky this way.
3) Give an idea of the sky clarity by noting the magnitude of the faintest star you could just see with averted vision in the general area of sky you were facing. This MUST be estimated using exactly the same degree of concentration as when watching for meteors; do not strain to see a star just a little bit fainter! If this changed notably over time (by more than 0.2 to 0.3 magnitudes), keep a check on how that altered at about 20-minute intervals. If clouds were present, note the percentage of your observing view the clouds covered at similar intervals (so if the sky is clearer elsewhere, turn to face that way instead).
4) Give a count of how many Perseid meteors and how many non-Perseid meteors you saw. Perseids will be moving swifter than many of the other meteors you are likely to see in mid August, providing their paths are longer than roughly 10 degrees. Perseids will be moving away from their radiant, a few degrees northeast of Eta Perseii at the maximum, but can appear in ANY part of the sky. Their paths will tend to be longer the further from the radiant they are (and very short close to the radiant - so don't look here all the time, because short-pathed meteors are much harder to spot). To tell if the meteor may have come from the Perseid radiant, trace the path back across the sky from where it happened in a dead straight line. You can use a rigid straight-edge like a ruler or broom-handle to help with this.
For best results, make sure you'll be warm and comfortable while observing, and watch as much clear sky as practical within those constraints, ideally centring your vision about 20-40 degrees from the Perseid radiant, and at least 30-40 degrees above the horizon. Don't look fixedly in only one direction, but make any head movements slowly and steadily, so as not to miss meteors.
Good luck, and clear skies!
Meteor Director, Society for Popular Astronomy.
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