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(meteorobs) LEONIDS-1996: ZHRs in So. Calif

           ZENITH HOURLY RATE CALCULATION FOR LUNSFORD/ASSMUS DATA
                THE LEONID PEAK NIGHT (November 16/17, 1996)


     Here are presented LEONID ZHR rate estimates [calculated as per
  Jenniskens(1994)] for visual data collected by Robert Lunsford and Joseph
  Assmus. These data were collected in Descanso California, USA at the Zay
  Observatory.  ZHR was not calculated for Bob's first interval because
  radiant was still below horizon.  For Bob and my Observer Perception
  Coefficents (Cp), I again adopted Jenniskens (1994) method and used the
  following equation:

                     Cp =  (Ns * r^(6.5-Lm)) / 10 * Teff

     Ns = number of observed sporadics,
      r = 3.4 (SPO population index)
     Lm = avg limiting magitude .


     According to Jenniskens (1994), Cp is  "... a standard observer's
  probability of detecting (sporadic) meteors... Cp varies between 0.4 and 2.5
  and has a median value close to 1 (=no correction)".  Before presenting our
  ZHR results, though, I would like to pose some questions to anyone
  interested in answering:

       1.     Cp, of course, can not be a true probability measure because, by
           definition, it CAN assume values > 1.0.  What does a Cp>1 mean?
           Should the Cp really be referred to as a "probability"?  Can
           observers with Cp>1 be considered expert meteor observers?
           Could it be that observers with Cp>1 tend to missclassify SPOs more
           ofter than those observers with Cp<=1?  (Just kidding.. tho in a
           sense Im not.)


       2.     In calculating the ZHR for a given night's data, what would be a
           more appropriate approach ...  deriving a Cp value based on that
           night's SPO counts
                                       OR

           creating and continually updating a personal, "historical" Cp
           (i.e. a Cp based on the sum of ALL ones observations)?   I would
           guess a Cp based on that night's SPO count and Lm may more
           closely reflect the oberserver's "perception" on that given night.
           How do the DMS/Team Delphinus do it?

     For ZHR calc's,  I used the following equation (Jenniskens, 1994):
  Also, for the LEO population index, r, I used the same value as Casper(DMS)

                   ZHR = N/Teff * r^(6.5-Lm) * sin(Hr)^(-g) * Cp

     where  r = 2.8,
            g = 1.4 (gamma)
           Hr = height of the radiant,

    Standard error measure (SEM) for ZHR = ZHR/Sqrt(N).



                         LUNSFORD DATA

  INTERVAL       Teff   Lm      nLEO  nSPO    ZHR(Leo)  SEM(+/-)

06:30-07:30 UT   1.0   6.42       1     9
07:30-08:30 UT   1.0   6.41       8     4      99.49     35.17
08:30-09:30 UT   1.0   6.40      19     4      74.81     17.16
09:30-10:30 UT   1.0   5.99      17     6      54.76     13.28
10:30-11:30 UT   1.0   6.13      16     7      30.64      7.66
11:30-12:30 UT   1.0   6.33      30     8      37.44      6.84
12:30-11:30 UT   1.0   5.77      35     9      67.78     11.46



                          ASSMUS DATA

08:00-09:00 UT   .94   6.10      15     3      119.00    30.726
09:00-10:00 UT   .95   6.10      12     7       44.70    12.902
                             -break-
11:45-12:45 UT   .93   6.00      18     2       31.35     7.389
12:45-13:00 UT   .70   6.00      13     5       27.33     7.587



     From these ZHR estimates, it sure seems like we here in S Cal caught the
 back side of the activity slope.  Any commentary?


 Joseph