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The California Meteor Society |
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The California Meteor Society |
Starting in 1989, the Perseid meteor shower has produced a series of meteor outbursts: periods of 1-2 hours during which rates dramatically increased, bright fireballs flashed the sky and persistent trains blew in the upper atmosphere winds. Peak rates gradually increased until 1992, when parent comet P/Swift-Tuttle passed the nearest point to the Sun in December of that year. After that, rates have gradually decreased. Each year, the outbursts are visible at a different geographic location. The last Perseid outburst visible from the Bay Area was in August of 1994, when the shower peaked at about 4 o'clock.
1997 is perhaps our last chance to see another such outbursts of the
Perseid shower on the west coast. This year the Perseid meteor stream is
expected to have an outburst between midnight and 2 am PDST on August 12.
Rates should increase to about twice the normal Perseid activity and a
relatively large number of bright meteors is expected to appear. Rates are
expected to be low in the first few hours, then around midnight rates will
sharply rise, while staying at about the same level of activity for the
rest of the night. The first quarter moon will not disturb meteor
visibility much as it will set just about at the time of the peak of the
outburst. (See Table 1 for the predicted outburst rates.)
If you are interested in observing the Perseids this year, then consider participating in our observing campaign, and watch one of nature's most impressive phenomena. The meteor observing will start at 9:00 PM commence through the night until morning dawn. This is to allow for some uncertainty in the time of the peak.
It is possible also to contribute to the project from your own favorite observing spot. Meteor observers through out Northern California can contribute by recording meteor times and making plots on star charts. Meteor photographers can also join the network from other sites as long as the shutter opening and closing times are recorded to within 1 second and the camera is pointed towards the San Jose area. No tracking on the cameras is required.
To prepare for the observing on the night of August 11th/12th, two meteor observing training sessions will be held on Fremont Peak Observatory on the evenings of Saturday August 2nd, (to coincide with the AANC Star-B-Que) and Saturday August 9th. Participants will get instruction on observing and two hours of practice. We will gather at FPO at 9 PM on both Saturdays and start observing at about 10 PM until midnight. Please be prepared for meteor observing by bringing a lounge chair or ground cloth, a clip board, a red flashlight, an accurately set watch, proper night clothing, and an adventurous attitude.
Contact: Mike Koop
California Meteor Society Coordinator: Perseids 97
email: koopm@best.com
Phone: (408) 473-6315
Contact: Dr. Peter Jenniskens ,
The SETI Institute
NASA Ames Research Center
Mail Stop 239-4
Moffett Field, CA 94035-1000
Solar Longitude (1950) UT PDST h radiant h moon ZHR #visible % outburst
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dusk
138.831 4 09pm 9.5 33.5 71 4 0
138.870 5 10pm 13.7 26.8 72 7 2
138.910 6 11pm 18.6 18.2 77 14 6
138.951 7 12pm 25.1 8.2 93 25 21
138.983 peak of outburst
138.991 8 01am 32.3 -2.5 119 50 38
139.030 9 02am 40.2 -14.0 87 47 14
139.070 10 03am 48.2 -25.6 79 52 4
139.111 11 04am 56.0 -37.1 77 60 1
139.151 12 05am 62.9 -48.4 78 66 0
dawn
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Table 1: Observing conditions on August 11th/12th, 1997, for California (-122W, +37N). Columns list the solar longitude (B1950), the Universal Time, the Pacific Daylight Savings Time, the altitude of the radiant (hr) in degrees, the altitude of the Moon (hm) in degrees, the total Perseid Zenith Hourly Rate, the actual number of Perseids that appears per hour visible for a single observer in good dark skies, and the percentage of those meteors that are part of the outburst.