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(meteorobs) Data and prelim. ZHR Leonid storm LANMA




From: Marco Langbroek
      Dutch Meteor Society (DMS)

Hello all,

I finally have my data of the November 17-18 Leonid storm ready. Below, I 
will give a table with raw data, and:

a PRELIMINARY ZHR curve from my data for the period 1:05-4:14 UT. Reduction 
procedure can be found in Peter Jenniskens paper in A&A 295 (1995), 206; 
and in my paper in Meteoritics & Planetary Science 34 (1999), 137. I used 
gamma=1.4 in radiant altitude correction, r=3.5 (as resulting from my 
mag. estimates: 3.5 +- 0.8. No magnitude data from period 1:49-2:49!!) in 
limiting magnitude correction, and my Cp is 1.4. ZHR's are only given for 
radiant elevations above 20 degrees.

A fit to the ascending and descending branches gives a maximum at 2:03 UT 
with a maximum activity equivalent to a ZHR of about 3200. Indeed, this is 
where I have my highest count (39 Leonids in one minute at 2:03 UT, Lm 
+6.6; this one minute count taken face value provides a ZHR of 3587 +- 
575). With an uncertainty of only a few minutes, David and Rob's peak 
prediction thus was correct. They only need to adjust their activity level 
prediction model slightly!

The slopes of the peak are well defined, symmetric and suggest B=20 (see 
above papers). After 3:00 UT with ZHR's below 200, there is some 
indication of a background taking over.

- Marco Langbroek
  Dutch Meteor Society (DMS)


table below; given are time midst (UTC), effective time of interval in 
minutes; number of Leonids; ZHR ( - : ZHR not calculated, radiant below 20 
degrees)


obs: Marco Langbroek     LANMA
date: November 17-18, 1999
loc.: Xalos, Spain, 38d 43' 37" N, 00d 01' 30" E
-----------------------------------------
UT       min   Nleo      eZHR
23:58    45    9         -
00:33    20    14        -
00:58    13    17        -
01:10    9     34        640 +- 110
01:22    12    71        847 +- 100
01:33    10    68        761 +- 92
01:46    8    130        1736 +- 152
01:56    9    232        2468 +- 162
02:07    8    248        2815 +- 179
02:22    7    167        1845 +- 143
02:32    7    115        1191 +- 111
02:38    6     77        928 +- 106
02:53   10     82        533 +- 59
03:03    5     39        512 +- 82
03:11    9     53        305 +- 42
03:23    5     21        251 +- 55
03:38   10     35        185 +- 31
03:46    6     18        155 +- 31
04:05    6     14        115 +- 31
04:11    6     13        105 +- 29
-----------------------------------------
note: when plotted in a diagram with the ZHR axis logarithmic,
the activity profile has a nice well defined shape! See also
the A&A paper mentioned earlier.


table: magnitude data (number of Leonids per magnitude class)
---------------------------------------------------------------
                -3   -2   -1   0   +1   +2   +3   +4   +5   +6   
23:35-01:49 UT   1    2    8   4   17   51   102  89   41   20
02:49-04:14 UT   0    0    5   6   11   45    80  70   38    5
TOTAL            1    2   13  10   28   96   182 159   79   25
--------------------------------------------------------------


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