(meteorobs) Origin of ZHR?

[belatrix]

And thus began an endless source of misunderstanding to complete 
newcomers to meteor/sky watching LOL

On 13/05/2007, at 1:27 AM, Julian Parks wrote:

> Under Section 15.6, Zenithal Hourly Rate, and Zenithal Magnitude,
> p.202, the 1955/1957 ed. of Sedgwick's, " Observational Astronomy for
> Amateurs," and I quote,  "The ZHR is derived from the observational
> data by applying corrections for the altitude of the radiant and for
> moonlight, if any; generally, however, observations for statistical
> purposes are not made when there is strong moonlight."
>
> "If R is the observed hourly rate, then Rc (the HR corrected for
> radiant altitude a) is given by
>
>                         Rc = R cosec (a+6º)
>
> The correction for moonlight depends upon the lunar phase and the
> incidence of diffusing matter in the atmosphere, and must be
> determined empirically by comparing the numbers per magnitude with
> similar figures relating to a previous, moonless, return of the
> swarm."  End quote.
>
> Julian Parks
> Rego Park, NY
>
>
>
>
> --- In meteorobs at yahoogroups.com, meteors at ... wrote:
>>
>> Julian,
>>
>>> From what I've been able to determine, Opik, Porter, and Oliver all
>> addressed parts of the issue, so maybe Sedgwick is the one who put
> it all
>> together. I'll check my County Libtary for the bood.
>>
>> Is there a copy of the formula?
>>
>> Wayne
>>
>>
>>> Rich,
>>>
>>> If you have a copy of Sedgwick's, "Observational Astronomy for
> Amateurs,"
>>> either the 1955/1957 edition or the fourth edition there is a
> reference to
>>> Meteor Counts and Hourly Rates in Section 15.5 and to Zenithal
> Hourly
>>> Rate, and Zenithal Magnitude in Section 15.6 and a Bibliography
> for E.
>>> Opik, J.G. Porter, C.P. Oliver, et. al. who researched this
> area.  From
>>> the Bibliography the dates I see referred to are 1920, 1921,
> 1923, 1930,
>>> 1931.  These cites are from the Harvard Circ. and ``Journal of
> the British
>>> Astronomical Association among others.  There is also mentioned
> in Section
>>> 15.5 statistical work in the mid-nineteenth century by a Gravier
> and
>>> Schmidt.  Whatever that statistical work is I do not know.
> Sounds like a
>>> trip to the library.
>>>
>>> Hope this helps.
>>>
>>> Julian Parks
>>> Rego Park, NY
>>>
>>> ----- Original Message -----
>>> From: "Richard Taibi" <rjtaibi at ...>
>>> To: <meteorobs at ...>
>>> Sent: Friday, May 11, 2007 9:02 PM
>>> Subject: (meteorobs) Origin of ZHR?
>>>
>>>
>>>> Does anyone know who developed the concept of the Zenithal
> Hourly Rate,
>>>> and
>>>> when it was proposed?
>>>>
>>>> Thanks!
>>>>
>>>> Rich
>>>>
>>>>
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>>
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>
>
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