[BAA 00157] Perseids 2004

[Rick]

Observing Opportunity - Perseids 2004

The Perseids, one of the three most active reliable annual meteor showers, reach maximum this week, and are met with increasingly favourable lunar phasing as the Moon heads towards New on August 16. Dark sky conditions will extend well into the post-midnight hours by the time of the Perseid maximum close to August 12.

In 2004, peak is expected around Aug 12d 07h UT, making it likely that the highest Perseid rates will be found late on the Wednesday night to Thursday morning of August 11-12. Activity should still be high in early evening on August 12-13. Peak Zenithal Hourly Rate (corrected for radiant elevation and sky transparency) typically reaches 80-100, corresponding to observed rates of as much as 60-70 meteors/hr from a clear dark location with the radiant high in the sky (as found late in the night: the Perseid radiant at maximum lies at RA 03h 04m Dec +58o, near the Perseus/Cassiopeia border). Strong activity is found for several nights to either side of maximum, and even novice observers should find watches between now and Aug 15-16 productive. The shower then declines rapidly, and is over by August 20.

Reasonable activity was already in evidence over the weekend just past, and several regular observers have begun to submit results. Reports of visual watches made by the Meteor Section's standard methods (outlined on http://www.britastro.org/meteor, and in the August Journal of the BAA) will be welcomed by the Director.  Remember that Delta and Iota Aquarids, Capricornids and Alpha Capricornids, Alpha Cygnids and sporadic meteors should all be recorded, if seen, alongside the Perseids!

Modelling of the Perseid stream by Esko Lyyttinen  and Tom Van Flandern suggests we may enjoy enhanced activity early on Aug 11-12, an again close to the regular maximum later the same night. We need as many observations as possible to verify whether or not this happens.

Photographers often find the Perseids, with their high proportion of bright events close to maximum, a productive shower. Observers hoping to capture meteors on film may enjoy success by carrying out 10-15 minute exposures on ISO 400 film with cameras equipped with standard 50 mm or wide-angle 28 mm lenses at f/2 to f/2.8, aiming in the direction of Cygnus early in the night, and the Square of Pegasus later on.

Following a lean year due to moonlight interference in 2003. regular meteor observers should need little encouragement to make the most of this opportunity/. We can only hope that the current humid, cloudy conditions over the British Isles will pass through as forecast through midweek. Those fortunate enough to  find themselves under clear skies are urged to make the best possible use of them!

Neil Bone
Director, BAA Meteor Section
9th August 2004

[Rick]

Rumour suggests there may be a peak of activity round 21:00 UT (22:00 BST) on Wednesday evening, so I guess the clouds will stay til then, at least...