(meteorobs) [Meteorobs] ZHR Table

[Vit M]

Hi! You don't need a table -- there is a formula (see 
http://www.namnmeteors.org/guidechap8.html):

"The zenithal hourly rate is a means by which different observers can convey 
their results to each other. Of course, this is the ideal condition to 
observe meteors under. However, conditions are not always perfect. To make 
matters worse, the human factor is a variable that makes ZHR results less 
precise. There are several methods to finding a ZHR. Some are more accurate 
than others and are quite involved in calculations. Variables to consider 
include clouds, limiting magnitudes, observing periods, the radiant's zenith 
distance, geographical latitude of the observer, and the observer's own 
perception. The following method does not take all of these variables into 
account. But this method from Neil Bone's book, Meteors will serve our 
purposes here as an introduction to the subject.

With:
HR = observed hourly rate; r = population index; LM = your average limiting 
magnitude; and A = altitude of the shower's radiant above the horizon in 
degrees

a) Formula with an LM above 6.5

       (HR) (r)^1-(LM - 6.5)
ZHR = ----------------------
              Sine A

b) Formula with an LM below 6.5

        (HR) (r)^6.5-LM
ZHR = -------------------
             Sine A

Example: Geminids with clear skies and no obstructions.

Assume:
HR = 57 meteors seen for 1 hour
r = population index for Geminids is 2.6
LM = average limiting magnitude for that hour is 5.7
A = the shower's radiant above the horizon for that hour is 60 degrees


        (HR) (r)6.5 - LM
ZHR = -----------------------
            Sine A


       (57) (2.6)6.5 - 5.7
     = -----------------------
         Sine 60 degrees


           (57) (2.6).8
     = -----------------------
            .866025404


             57 X 2.14
     = -----------------------
            .866025404


               121.98
     =   ---------------------
            .866025404


     =    140 ZHR"



Best regards,

Vitaly.



==============================================================================

Sat, 24 Oct 2009 19:59:06 +0000, richard hill <dwarfnova at hotmail.com> 
писал(а):

> 
> H, All!
> 
> 
> 
> Can anyone tell me where I can find a table to convert observed rates to 
>ZHR's?
> 
> 
> 
> Rick
> 		 	   		  
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