Eta-Aquarids 2000 - II

The large number of observing reports coming in after the first Shower Circular about the eta-Aquarids allowed an update of the activity graph. The shower appears to exhibit a period of about three days with ZHRs above 50. The data set does not allow to conclude about the fluctuations; yet the broad maximum and the maximum ZHR of ~60 are a clear result of this preliminary compilation.

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Date   Time (UT)  Sol.  nETA  nObs  ZHR   +/-
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Apr 29   1800    39.71    1    2     2.4  1.7
Apr 30   1740    40.67   18    4    18    4.1
May 01   2210    41.82   34    5    28    4.6
May 03   0050    42.90   33    4    36    6.1
May 04   0520    44.05   15    4    36    8.9
May 04   1820    44.58   17    5    54   13
May 05   0040    44.84   64    8    65    8.0
May 05   1330    45.35   86    6    48    5.2
May 06   0140    45.84  105   11    56    5.4
May 06   0840    46.13   35    7    35    5.9
May 06   1610    46.43  119    6    51    4.7
May 07   0630    47.01   61    8    38    4.8
May 08   0630    47.98   57    4    60    7.8
May 10   0210    49.73   23    4    24    5.0
May 11   0120    50.67    4    2    26   12
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Solar longitudes refer to equinox J2000. Average times are given with 10-minute accuracy though often refer to many hours coverage. The average ZHR was computed by <ZHR> = sum n / sum(Teff/C) where Teff is the effective observing time, C is the total correction according to limiting magnitude, possible field obstruction and radiant elevation as sin(hR). The ZHR refers to a limiting magnitude of +6.5 and a radiant elevation of 90 degrees. nETA is the number eta-Aquarids seen, nObs is the number of observing periods contributing to the average; the number of individual observers is smaller in most of the cases.

This preliminary compilation was based on the reports of the following observers:

ATAJU Jure Atanackov (Slovenia), BUCAN Andreas Buchmann (Switzerland), CERJA Jakub Cerny (Czech Republic), COOTI Tim Cooper (South Africa), DAVMA Mark Davis (USA), DIAAS Asdai Diaz Rodriguez (Cuba), HOLDA David Holman (USA), JOHCA Carl Johannink (the Netherlands), KONKH Khalil Konsul (Jordan), KOUWE Wen Kou (China), LANMA Marco Langbroek (the Netherlands), LINMI Mike Linnolt (USA), MARAD Adam Marsh (Australia), MARPI Pierre Martin (Canada), MATMI Michael Matiazzo (Australia), MCLAL Alex M'clintock (Spain), MISKO Koen Miskotte (the Netherlands), MOLSI Sirko Molau (Germany, from Jordan), MOSSC Scott Moser (USA), MOTER Erick Mota Perez (Cuba), NATSV Sven Nather (Germany, from Morocco), NITMI Mirko Nitschke (Germany, from Jordan), TELKH Khaled M. Tell (Jordan) and YOUKI Kim Youmans (USA).