zenithal hourly rate


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zenithal hourly rate

[′zē·nə·thəl ′au̇r·lē ′rāt]
(astronomy)
The number of meteors in a meteor shower which would be observed per hour if the radiant of the meteor shower were overhead and there were no moonlight.
References in periodicals archive ?
Such counts are analyzed to yield the shower's zenithal hourly rate during the time you were watching.
But Lyytinen is predicting many more, with a zenithal hourly rate (ZHR) reaching a few hundred.
Such a count can be analyzed to yield the shower's zenithal hourly rate at the time you were watching.
Rainer Arlt of the International Meteor Organization has reduced counts made by 144 observers to the standard zenithal hourly rate (ZHR), in order to produce the preliminary graph of the shower's activity below.
The purpose of all this is to give your numbers meaning--that is, to make them convertible to the standard measure of the true meteor activity, the zenithal hourly rate or ZHR.
He reported an outburst of Bootids from about 19:00 UT on June 22nd to 1:00 UT on June 24th, with a very respectable peak zenithal hourly rate around 30 near 11:00 UT on June 23rd.
This implies that the shower's zenithal hourly rate, or ZHR (the number of meteors a single observer would see if the sky were dark and the shower's radiant were at the zenith), was around 80, the shower's textbook average.
Geminids: This shower is generally the highlight of the meteor year, with high zenithal hourly rates.