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(meteorobs) More preliminary ZHR results (Europe too)

Hello again,

Below some VERY preliminary ZHR-results from our Dutch observations, to 
add to the preliminary ZHR for california I communicated earlier. Again: 
please regard this as an indication of rate level only. It is based on 
data from 3 observers: Carl Johannink, Koen Miskotte and me (=Marco 
Langbroek).

In general, ZHR's were around ~50 for early november 17 as observed from 
Northwest Europe. Unfortunately, our observing interval was short due to 
clouds. The next night, 17/18, saw a ZHR that decreased clearly over the 
night, from about ~40 to ~30. Coupled to the ZHR ~115 seen from 
California (note: based on Bob's data only, so be carefull!), this agrees 
excellently with a B~1 component peaking at around ZHR ~115 (annual + 
outburst combined: outburst only ~100) above the western USA, with B 
describing rate behaviour as in the next equation:

ZHR = ZHR_max * 10^-B|l-l_max|   (See Astron. Astroph. 295 (1995), 206)

...with l= solar longitude

This means that a similar broad B ~1 (and bright) component as in 
1994-1995-1996 has been present, this time with a peak ZHR near 100.

It is not clear whether a narrow peak was also present, as in 1996. 
Perhaps Bob and some others saw the onset after 13:00 and the narrow peak 
then might have peaked just after the end of the Californian time window, 
over the western Pacific perhaps. But as George noted, 'storm'-rates have 
not been seen by Californians themselves, judging from the reports and 
Bob's data.

Below some ZHR's for the European intervals, as described above, 
calculated for r=2.0 with gamma=1.4 and perception taken into account 
(Carl: 1.0:  Koen: 1.2;   Marco: 1.4).

Nov 17
UT     ZHR  +-
1:30   50   8


Nov 18
UT     ZHR   +-
1:45   42    5
3:42   28    4


Add these to the values from Bob's observations from west USA send 
earlier (ZHR's around 115, except for last hour which might have been 
higher). The outburst was present for about one day, with Europe seeing 
rates going up the one night and down the other, and the USA having the 
privilege of the peak.


-Marco Langbroek
Dutch Meteor Society