En astronomie, le taux horaire zénithal (en abrégé THZ ; en anglais Zenithal Hourly Rate, ZHR) d'une pluie de météores est la valeur maximale du nombre d'étoiles filantes qu'un observateur idéal pourrait voir si le radiant se situait à son zénith sous un ciel parfaitement transparent.

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  • En astronomie, le taux horaire zénithal (en abrégé THZ ; en anglais Zenithal Hourly Rate, ZHR) d'une pluie de météores est la valeur maximale du nombre d'étoiles filantes qu'un observateur idéal pourrait voir si le radiant se situait à son zénith sous un ciel parfaitement transparent. Les conditions d'observation étant bien souvent loin d'être idéales (radiant plus bas sur l'horizon, pollution lumineuse), le THZ surestime le nombre de météores observés, il sert cependant à caractériser les essaims entre eux.Portail de l’astronomie Portail de l’astronomie
  • En astronomía, la tasa horaria zenital (THZ, también escrito tasa horaria cenital, THC) es el número máximo calculado de meteoros que un observador ideal podría ver bajo un cielo perfectamente claro y con el radiante ubicado directamente en el zenit. Este valor es dado en términos de meteoros por hora. En aquellos casos que un nivel de actividad se presente elevado durante un período menor a una hora, se utiliza la THZ equivalente (THZE) como si hubiese mantenido durante una hora.Este parámetro define el nivel de actividad de una lluvia de estrellas.
  • In astronomia, il Tasso Orario Zenitale, identificato in italiano con la sigla TOZ e in inglese con ZHR, Zenithal Hourly Rate, di uno sciame meteorico è il numero di meteore che un osservatore sarebbe in grado di osservare in un'ora, sotto un cielo buio e terso (quindi con magnitudine limite 6,5), se il radiante dello sciame fosse allo zenit.Quando lo ZHR supera il valore 1000, si parla di tempesta meteorica.
  • 天頂出現数(てんちょうしゅつげんすう、Zenith Hourly Rate(ZHR))は、流星群の流星の出現数を表現する数値である。「天頂1時間流星数(てんちょういちじかんりゅうせいすう)」、「天頂修正出現数(てんちょうしゅうせいしゅつげんすう)」などとも呼ばれる。
  • Em astronomia, a Taxa Horária Zenital (THZ ou, em inglês, ZHR - Zenithal Hourly Rate) de uma chuva de meteoros (chuva de estrelas), é o número de meteoros que um observador poderá ver numa hora, sob condições de céu limpo, escuro (limite da magnitude aparente de 6.5) e se o radiante da chuva estiver no zénite. No entanto, a taxa que pode ser efectivamente observada é quase sempre inferior e tende a diminuir à medida que o radiante se aproxima do horizonte.== Referências ==
  • De Zenithal hourly rate (ZHR) is een maat voor de activiteit van een meteorenzwerm. De ZHR geeft het aantal met het blote oog zichtbare meteoren weer, dat per uur kan worden waargenomen tijdens het maximum van een zwerm, onder ideale omstandigheden. Het is het aantal meteoren dat zou worden gezien bij een grensmagnitude van 6,5 indien de radiant zich in het zenit zou bevinden.Dit maximum wordt in de praktijk zelden bereikt.
  • In astronomy, the Zenithal Hourly Rate (ZHR) of a meteor shower is the number of meteors a single observer would see in one hour under a clear, dark sky (limiting apparent magnitude of 6.5) if the radiant of the shower were at the zenith. The rate that can effectively be seen is nearly always lower and decreases the closer the radiant is to the horizon.The formula to calculate the ZHR is:whererepresents the hourly rate of the observer. N is the number of meteors observed, and Teff is the effective observation time of the observer.Example: If the observer detected 12 meteors in 15 minutes, their hourly rate was 48. (12 divided by 0.25 hours).This represents the field of view correction factor, where k is the percentage of the observer's field of view which is obstructed (by clouds, for example).Example: If 20% of the observer's field of view were covered by clouds, k would be 0.2 and F would be 1.25. The observer should have seen 25% more meteors, therefore we multiply by F = 1.25.This represents the limiting magnitude correction factor. For every change of 1 magnitude in the limiting magnitude of the observer, the number of meteors observed changes by a factor of r. Therefore we must take this into account.Example: If r is 2, and the observer's limiting magnitude is 5.5, we will have to multiply their hourly rate by 2 (2 to the power 6.5-5.5), to know how many meteors they would have seen if their limiting magnitude was 6.5.This represents the correction factor for altitude of the radiant above the horizon (hR). The number of meteors seen by an observer changes as the sine of the radiant height in radians.Example: If the radiant was at an average altitude of 30° during the observation period, we will have to divide the observer's hourly rate by 0.5 (sin 30°) to know how many meteors they would have seen if the radiant was at the zenith.
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  • En astronomie, le taux horaire zénithal (en abrégé THZ ; en anglais Zenithal Hourly Rate, ZHR) d'une pluie de météores est la valeur maximale du nombre d'étoiles filantes qu'un observateur idéal pourrait voir si le radiant se situait à son zénith sous un ciel parfaitement transparent.
  • In astronomia, il Tasso Orario Zenitale, identificato in italiano con la sigla TOZ e in inglese con ZHR, Zenithal Hourly Rate, di uno sciame meteorico è il numero di meteore che un osservatore sarebbe in grado di osservare in un'ora, sotto un cielo buio e terso (quindi con magnitudine limite 6,5), se il radiante dello sciame fosse allo zenit.Quando lo ZHR supera il valore 1000, si parla di tempesta meteorica.
  • 天頂出現数(てんちょうしゅつげんすう、Zenith Hourly Rate(ZHR))は、流星群の流星の出現数を表現する数値である。「天頂1時間流星数(てんちょういちじかんりゅうせいすう)」、「天頂修正出現数(てんちょうしゅうせいしゅつげんすう)」などとも呼ばれる。
  • Em astronomia, a Taxa Horária Zenital (THZ ou, em inglês, ZHR - Zenithal Hourly Rate) de uma chuva de meteoros (chuva de estrelas), é o número de meteoros que um observador poderá ver numa hora, sob condições de céu limpo, escuro (limite da magnitude aparente de 6.5) e se o radiante da chuva estiver no zénite. No entanto, a taxa que pode ser efectivamente observada é quase sempre inferior e tende a diminuir à medida que o radiante se aproxima do horizonte.== Referências ==
  • De Zenithal hourly rate (ZHR) is een maat voor de activiteit van een meteorenzwerm. De ZHR geeft het aantal met het blote oog zichtbare meteoren weer, dat per uur kan worden waargenomen tijdens het maximum van een zwerm, onder ideale omstandigheden. Het is het aantal meteoren dat zou worden gezien bij een grensmagnitude van 6,5 indien de radiant zich in het zenit zou bevinden.Dit maximum wordt in de praktijk zelden bereikt.
  • En astronomía, la tasa horaria zenital (THZ, también escrito tasa horaria cenital, THC) es el número máximo calculado de meteoros que un observador ideal podría ver bajo un cielo perfectamente claro y con el radiante ubicado directamente en el zenit. Este valor es dado en términos de meteoros por hora.
  • In astronomy, the Zenithal Hourly Rate (ZHR) of a meteor shower is the number of meteors a single observer would see in one hour under a clear, dark sky (limiting apparent magnitude of 6.5) if the radiant of the shower were at the zenith. The rate that can effectively be seen is nearly always lower and decreases the closer the radiant is to the horizon.The formula to calculate the ZHR is:whererepresents the hourly rate of the observer.
  • Зенитното часово число (на английски: Zenithal Hourly Rate, ZHR) на метеорен поток представлява броя метеори, които могат да бъдат наблюдавани в рамките на един час при ясно нощно небе (гранична звездна величина равна на 6,5) когато радиантът на метеорния поток се намира в зенита.В случаите, когато активността на метеорния поток трае под един час, се говори за еквивалентно зенитно часово число (EZHR), което има смисъла на онази стойност на ZHR, която би имал същият поток, ако активността му бе продължила един час.Понятието ZHR се въвежда около средата на 20 век, с цел да се направят възможни сравненията на наблюденията на метеорните потоци.ZHR зависи от гъстотата на метеорния рой, както и от разстоянието между Земята и най-голямото сгъстяване в роя, в момента на срещата на Земята с роя.
rdfs:label
  • Taux horaire zénithal
  • Tasa Horaria Zenital
  • Tasso orario zenitale
  • Taxa horària zenital
  • Taxa horária zenital
  • Zenitalna liczba godzinna
  • Zenithal Hourly Rate
  • Zenithal Hourly Rate
  • Zenithal hourly rate
  • Зенитно часово число
  • Зенитное часовое число
  • 天頂出現数
  • 정점 시율
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