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(meteorobs) Fwd: 1999 Lyrids
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I M O S h o w e r C i r c u l a r
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LYRIDS 1999
The number of Lyrid observations which have reached the Visual
Commission is not large. Reports by 13 observers as listed
below came in during the last week. We are very grateful to
these quick reports allowing a first look at the 1999 Lyrid
activity.
The ZHR profile indicates slightly higher activity of the
Lyrids in 1999 compared with most of the recent years which
showed maximum activity of ZHR~15 to 20. However, 6 out of
the 7 periods averaging to the highest ZHR of 32 in the early
morning of April 23 comprise the reports of only two observers
at the same location.
If the enhanced activity is confirmed by additional observations,
it would not manifest an outburst in the sense of the 1982 or older
activity peaks, since those were very short in duration. The
reports giving ZHR=32 cover the period April 22, 2315 -- April 23,
0216 UT and do not show a clear peak pattern. The centre at a
solar longitude of 32.5 deg agrees moderately well with the maximum
of the annual Lyrid activity between 32.0 and 32.4 deg.
BAKLA Lars Bakmann (Denmark)
EINSH Shlomi Eini (Israel)
ENZFR Frank Enzlein (Germany)
LEVAN Anna Levina (Israel)
LINMI Mike Linnolt (USA)
MARPI Pierre Martin (Canada)
MIKMR Mark Mikutis (USA)
MOUPH Philippe Moussette (Canada)
NATSV Sven Nather (Germany)
RENJU Jurgen Rendtel (Germany)
STOWE Wes Stone (USA)
VANER Erwin van Ballegoij (Aruba)
YOUKI Kim Youmans (USA)
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Date Time Sollong nObs nLYR ZHR +-
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1999/04/18 0820 27.9 4 10 6.1 3.8
1999/04/19 0400 28.7 8 15 3.0 1.5
1999/04/20 0255 29.6 11 30 4.8 1.8
1999/04/21 0045 30.5 6 28 7.9 3.0
1999/04/21 0815 30.8 6 21 6.5 2.8
1999/04/22 0225 31.5 6 33 22.7 7.9
1999/04/22 0715 31.7 5 28 14.9 5.6
1999/04/23 0045 32.5 7 50 32.4 9.2
1999/04/23 0855 32.8 4 41 11.8 3.7
1999/04/24 0850 33.8 2 6 5.7 4.7
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Solar longitudes are given with respect to equinox J2000.0;
the ZHR is computed with a population index r=2.9 and a zenith
correction exponent of gamma=1. nObs is the number of observing
periods in the average, it is not the number of different obser-
vers contributing. nLYR is the number of Lyrids seen in these
periods.
---
Rainer Arlt, 1999 April 27.
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