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Re: (meteorobs) Revised AMS Meteor & Meteor Showers FAQ



Jim Richardson wrote on the subject: Revised AMS Meteor & 
Meteor Showers FAQ:

> After some revision work by Bob Lunsford and myself, 
> comments and suggestions for improvements on the below 
> are welcome.

I just have a question on FAQ #8:

> 8. Does the published meteor rate for a shower really 
> represent what I should expect to see?
> <...>
> Below is a table showing actual expected values for the 
> major meteor showers, along with their corrected ZHR's.  
> ...  Four different rates are given for each shower, 
> under the following conditions:
>
>     (1) city sky or rural sky with full moon,
>     (2) suburb sky or rural sky with quarter moon,
>     (3) rural sky and moonless,
>     (4) calculated Zenith hourly Rate, ZHR.
>
> Date       Shower Name        (1)     (2)     (3)     (4)
> -----------------------------------------------------------
> Jan 3-4    Quadrantids         5      10       25     120
> Apr 21-22  April Lyrids        4       7       15      15
> May 4-5    Eta Aquarids        4       6       10      40
> Jul 28-29  Delta Aquarids      4       7       15      20
> Aug 12-13  Perseids           10      20       40     120
> Oct 21-22  Orionids            5      10       25      25
> Nov 3-13   Taurids             4       6       10      10
> Nov 16-17  Leonids             5      10       15      15
> Dec 13-14  Geminids           18      35       85      85
> Dec 21-22  Ursids              3       5       10      20

I was trying to "correlate" or match up the ratios here of 
column (1), full Moon, divided by column (3), moonless rural 
sky (which vary from .20 to .40) with a statement on the IMO 
Web site: "the full Moon reduces the observed number of 
meteors by a factor of about 10!"  I think there must be 
something that I'm missing about one or the other.  My only
guess is that perhaps the IMO statement is very general,
while the variance of the ratios of (1)/(3) in the table 
above may take into account the intrinsic brightness of the
showers -- some brighter than others.

I'd also be interested in the values that would appear in 
another column that combines BOTH city sky AND full Moon!  
(My guess would be to multiply (1) by the ratio of (1)/(3) 
-- resulting in a very dismal number indeed.)

Ed Cannon - ecannon@mail.utexasdot edu - Austin, Texas, USA
http://wwwvms.utexasdot edu/~ecannon/meteorlinks.html

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