Geminids '99: MS results

Ton Schoenmaker


Forward Scatter Meteor Observations of Geminids 1999

Observer:    Ton Schoenmaker
E-mail:      schoenmaker@nfra.nl
Location:    Roden, Netherlands (06 26' E, 53 08' N)
Frequency:   55.274 MHz 
Transmitter: Spanish TV channel E3 (video); transmitters in La Muela (30 kW), 
             Gamoniteiro (50 kW) and Aitana (60kW); all stations within 
             100 Hz of nominal frequency; distance 1650 km
Antenna:     4-element horizontal Yagi, geographical azimuth 105 degrees (ESE),
             elevation 15 degrees
Receiver:    Yupiteru MVT-9000 in FM mode; sensitivity 0.5 ÁV at 12 dB S/N
Observing:   audio (noise) signal from ear-phone socket was rectified and 
             recorded with a Servogor stripchart recorder with a chart speed 
             of 120 mm/hour

The somewhat uncommon geometry described above (receiving antenna pointing perpendicular to the direction of the transmitters) resulted in a peculiar observability function, so the counts are difficult to interpret in terms of Geminids activity. Apparently the observability function peaks at about 23h UTC when the main lobe of the 4-element yagi points to the radiant of the Geminids. The highest activity occurred on 13/14 December with counts of about 4 times the sporadics level. For the midpoint between The Netherlands and Spain the setting and rising of the radiant occurred at 11h30m and 15h30m UTC respectively. In the following table the uncorrected hourly counts for signals stronger than 0.1 ÁV are given. The activity on 21/22 December 1999 may be considered to be caused by sporadic meteors. Figure 1 shows the results graphically.

 
                      December 1999
 UTC |   12     13      14      15      16      21      22
-----------------------------------------------------------
  00 |    -    162     189     162      50       -      36
  01 |    -     98     158      73      43       -      50
  02 |    -     58      97      45      42       -      50
  03 |    -     69      96      43      33       -      48
  04 |    -     70     116      57      39       -      40
  05 |    -     50     103      47      30       -      39
  06 |    -     59      98      41       -       -      53
  07 |    -     49     106      30       -       -      35
  08 |    -     55     115      20       -       -      25
  09 |    -     53      74      34       -       -      30
  10 |    -     33      54      26       -       -      35
  11 |    -     19      24      18       -       -      26
  11h30m           setting of Geminids radiant
  12 |    -     12      26      21       -       -      21
  13 |    -      7      23       9       -       -      13
  14 |    -      6      12      10       -       -      11
  15 |    -      3       5       2       -       -       9
  15h30m           rising of Geminids radiant
  16 |    -      9      15       3       -       -      12  
  17 |    -     22      26       7       -       -      12
  18 |    -     62      63      13       -       -       9 
  19 |   99    136      94      25       -       -      18 
  20 |  117    152     124      27       -       -      25 
  21 |  154    166     177      40       -       -       - 
  22 |  176    199     197      58       -      35       - 
  23 |  186    214     195      63       -      54       -
-----------------------------------------------------------
 UTC |   12     13      14      15      16      21      22
     |                 December 1999

- no observations



Figure 1. The hourly counts of the Geminids on 12 - 16 December 1999. Apparently the observability function peaks around 23h UTC. At that time the main lobe of the receiving antenna points to the azimuth of the Geminids radiant.



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back.gif This page was last modified on January 3, 2000 by
Ton Schoenmaker and Casper ter Kuile