Geminids 2004, first results

A great amount of data has been reported by visual observers
already one day after the maximum night. The below activity
profile is based on 5511 Geminids seen by 46 observers.

The peak time of the shower is found near Dec 13, 20h UT.
The time given in solar longitude (position of Earth on its
orbit) is 262.1 degrees which is a bit early in the trend
found by Rendtel (WGN 32:2, 2004) suggesting 262.16-262.17
degrees.

However, variations in the steepness of the magnitude distributions (population index) as well as additional data
may shift the peak time a bit. These will be studied in
future analyses of the 2004 Geminids. It is very promising
that already at this early stage of analysis, a detailed
profile could be constructed.

The activity profile is listed below:

  
  ------------------------------------------------------  
  Date (UT) Time Solarlong nINT nGEM ZHR  
  ------------------------------------------------------  
  Dec 11.622 14:56 259.852 10 78 24 +- 3  
  Dec 12.333 07:60 260.575 27 240 33 +- 2  
  Dec 12.916 21:59 261.168 22 242 50 +- 3  
  Dec 13.062 01:29 261.317 33 314 83 +- 5  
  Dec 13.169 04:03 261.425 30 91 69 +- 7  
  Dec 13.249 05:59 261.507 28 141 111 +- 9  
  Dec 13.294 07:03 261.553 30 212 140 +- 10  
  Dec 13.351 08:25 261.611 29 166 125 +- 10  
  Dec 13.681 16:21 261.946 32 452 108 +- 5  
  Dec 13.776 18:37 262.043 23 102 143 +- 14  
  Dec 13.793 19:02 262.060 30 144 158 +- 13  
  Dec 13.816 19:35 262.084 25 137 163 +- 14  
  Dec 13.836 20:04 262.104 31 168 160 +- 12  
  Dec 13.857 20:34 262.125 30 183 141 +- 10  
  Dec 13.886 21:16 262.155 24 149 134 +- 11  
  Dec 13.905 21:43 262.174 36 257 139 +- 9  
  Dec 13.924 22:11 262.193 29 174 112 +- 8  
  Dec 13.945 22:41 262.215 25 257 147 +- 9  
  Dec 13.969 23:15 262.239 31 254 111 +- 7  
  Dec 14.013 00:19 262.284 30 304 113 +- 6  
  Dec 14.091 02:11 262.363 31 248 103 +- 7  
  Dec 14.145 03:29 262.418 36 124 84 +- 8  
  Dec 14.182 04:22 262.456 29 102 72 +- 7  
  Dec 14.233 05:36 262.508 31 108 53 +- 5  
  Dec 14.276 06:37 262.552 36 150 91 +- 7  
  Dec 14.322 07:44 262.598 30 372 114 +- 6  
  Dec 14.410 09:50 262.688 23 342 101 +- 5  
  ------------------------------------------------------  
  

I am very grateful to
Suzuka Asami (Japan), Ricardas Balciunas (Lithuania), Andreas Buchmann (Switzerland), Ed Cannon (USA), Hani Dalee (Jordan), Audrius Dubietis (Lithuania), Shlomi Eini (Israel), George W. Gliba (USA), William Godley (USA), Vishal Gokhale (India), Robin Gray (USA), Amir Hassanzadeh (Iran), Teresa Hernandez (Argentina), Javor Kac (Slovenia), Roy Keeris (the Netherlands), Richard Kramer (USA), Rhishikesh Kulkarni (India), Dafna Lavi (Israel), Anna Levina (Israel), Wei-qi Li (China), Alister Ling (Canada), Robert Lunsford (USA), Jin Ma (China), Qiang Ma (China), Xiaoyun Ma (China), Felix Martinez (USA), Bruce McCurdy (Canada), Wan-ya Nan (China), Markku Nissinen (Finland), Juergen Rendtel (Germany), Mikiya Sato (Japan), Tomoko Sato (Japan), Vladimir Slusarenko (Ukraine), Huang Song (China), Richard Taibi (USA), Kazumi Terakubo (Japan), Ouyang Tianjing (China), Tenho Tuomi (Canada), Yi-fei Wang (China), Larry Wood (Canada), Hao Wu (China), Quanzhi Ye (China), Kim Youmans (USA), Ilkka Yrjola (Finland), Wei Zhao (Cina), Jurga Zienjute (Lithuania)
for their quick and thorough reports.

The solar longitudes refer to equinox J2000.0, ZHRs are
computed with a population index of r=2.0 and a radiant
height correction of 1/sin(hR). nINT is the number of
observing periods in the average, nGEM the number of
Geminids involved.