Ann, When an observer is not directly under a meteor shower's radiant, they see less than the max zenithal hourly rate. The maximum predicated activity is a zenthal hourly rate of 100 per hour - or once every 30 seconds - if you are standing right under the shower radiant at the peak. For Utah, that will not occur. When the peak of the shower occurs, the radiant of the shower (see map) will be low in the northeast sky. The lower radiant altitude means that you will see a proportionally lower rate of meteors. I'd plan on seeing 20-30 per hour - or once every two or three minutes. This year's peak is predicted for 11:00pm on Sunday August 12 through 1:30 AM on Monday (Aug. 13 at 5:00-7:30 UTC). Radiant position maps; see the International Meteor Org site for more info http://www.imo.net/ At 11:00pm, the Perseid radiant will be low in the sky above the north-north-east horizon between Perseus and Cass near the Perseus Double Cluster. Expect to first see "grazers" - bright low meteors that enter the atomsphere nearly parallel to the ground, running northeast to southwest. As the Perseid radiant rises, its activity will be decreasing. Conversely, because the radiant is higher in the sky, you'll see more meteors. My experience at Little Mountain is these two factors balance out at around 20-30 per hour - or once every two or three minutes - with a good fireball every 10 minutes. Towards 1:00am the rate will drop off and becomes uninteresting. Little Mountain should be a good observing site this year. The radiant rises in the darkest northeast portion of the sky at that site. The light pollution from Salt Lake is in the west. You can see the Cygnus Great Drift in the eastern sky. The main problem is that 12:00-1:00am curtain call. -:) Currently, the county is putting in a new sewer up Emigration. You have to stop for 2 special construction traffic control lights - each about a 5 minute wait each - that feed through single lane road sections. Going up the back route on I-80 and East Canyon will be quicker. Conversely, the construction keeps the party crowd size down. Last Friday night - Saturday morning at Little Mtn - typically a pre-back to school party night, there were two cars and myself and little road traffic. For the last three weekends, no-see-ums have been heavy at this site even after midnight. Definitely wear DEET or other no-see-um repellant. Typically, I sit out in a lawn chair with a whole horizon sky chart. (Print from http://www.fourmilab.ch/yoursky/#Telescope ). Plot the direction of the meteors that you see on the chart. They will make a flashlight pattern pointing back to the radiant. I also set up mounted binoculars or a small scope pointed at the radiant. There are many more small meteors - not visible to the naked eye - that can be seen in the scope. It is instructive to compare the two. If you are lucky, a bright bolide or satellite will streak through the eyepiece while you are looking. At 1:30am, Mars will be at 5 1/2 degs altitude. The mountains will block it, but Mars should peek over the eastern ridgeline around 2:00am. (You'll be up anyway. So why not. -:) ) Last night, Mars was quite bright even near a third quarter Moon. - Kurt More background info: IMO Calendar http://www.imo.net/calendar/2007 search on term "Perseids" IMO Summary for the Perseids in the Calendar ================================= Maximum: August 13; 5h 7h30m UT - but see text ZHR = 100 . . . . The Perseids were one of the most exciting and dynamic meteor showers during the 1990s, with outbursts at a new primary maximum producing EZHRs of 400+ in 1991 and 1992. Rates from this peak decreased to ~ 100 -120 by the late 1990s, and in 2000, it first failed to appear. This was not unexpected, as the outbursts and the primary maximum (which was not noticed before 1988), were associated with the perihelion passage of the Perseids' parent comet 109P/Swift-Tuttle in 1992. The comet's orbital period is about 130 years, so it is now receding back into the outer Solar System, and theory predicts that such outburst rates should dwindle as the comet to Earth distance increases. However, some predictions suggested 2004 -2006 might bring a return of enhanced rates ahead of the usual maximum, and in 2004 a short, strong peak happened close to that anticipated pre-peak time. After that, activity seemed to be roughly normal in 2005, and the moonlit 2006 return was still to come when this text was prepared, but nothing untoward was predicted for 2007 in any case. An average annual shift of +0°05 in the gamma of the "old" primary peak had been deduced from 1991 -99 data, and allowing for this could give a possible recurrence time around 9h UT on August 13 . . . , if so a little after the most probable maximum, that of the "traditional" peak always previously found, which is given above. Another feature, seen only in IMO data from 1997 -99, was a tertiary peak at gamma = 140°4, the repeat time for which would be 15h UT on August 13. Observers should be aware that these predictions may not be an absolute guide to the best from the Perseids, and plan their efforts accordingly, so as not to miss out, just in case! Whatever happens, and whenever the peak or peaks fall around August 13, new Moon on August 12 creates perfect observing circumstances this year. For mid-northern latitudes, the radiant is sensibly observable from 22h -23h local time onwards, gaining altitude throughout the night. The UT morning-hour maxima suggested here would be best-viewed from across North America and northern South America, while the possible ~ 15h UT peak would fall best for Far Eastern Asia. Visual and still-imaging observers should need little encouragement to cover this stream, but telescopic and video watching near the main peak would be valuable in confirming or clarifying the possibly multiple nature of the Perseid radiant, something not detectable visually. Recent video results have shown a very simple, single radiant structure certainly. Radio data would naturally enable early confirmation, or detection, of perhaps otherwise unobserved maxima, assuming more than one takes place, if the timings or weather conditions prove unsuitable for land-based sites. The only negative aspect to the shower is the impossibility of covering it from the bulk of the southern hemisphere. End IMO excerpt ================================= _______________________________________________ Sent via CSolutions - http://www.csolutions.net