Difference: LeoNides2006en (1 vs. 2)

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META TOPICPARENT name="AgendaAstronomica2006En"
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Català Castellano English
 

Leonids 2006

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  (14th to 21st November 2006)
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  Traditionally, the Leonids are a very variable phenomenon; quite different from year to year. That is the reason for the substantial disagreements among the different predictions.
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Visió de la Terra que tindran les Leònides en el moment del màxim de la matinada del 19 de novembre
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Visió de la Terra que tindran les Leònides en el moment del màxim de la matinada del 19 de novembre
 
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The Earth as seen from coming Leonid meteors at the moment of maximum from 1932 trail at 4:55 UT on 19th November. Red line shows the border of hemisphere where the Moon is above horizon. Image from Maslov.
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The Earth as seen from coming Leonid meteors at the moment of maximum from 1932 trail at 4:55 UT on 19th November. Red line shows the border of hemisphere where the Moon is above horizon. Image from Maslov.
 
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The increment of meteor's activity will last for a week, however the most important maximum visible this year will happen during the early morning of the 19th November, at approximately 4:45 UT, (allow 5 minutes margin deriving from models). This maximum will be produced by the trace left behind by comet Tempel-Tuttle in 1932. Observers from western Europe will be the best situated since the radiant (the point from which shooting stars seem to come; Leo constellation in this case) will be near the zenith at the time of the maximum. Moreover, the Moon will not be a problem for observers as it will be nearly new.
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The increment of meteor's activity will last for a week, however the most important maximum visible this year will happen during the early morning of the 19th November, at approximately 4:45 UT, (allow 5 minutes margin deriving from models). This maximum will be produced by the trace left behind by comet Tempel-Tuttle in 1932. Observers from western Europe will be the best situated since the radiant (the point from which shooting stars seem to come; Leo constellation in this case) will be near the zenith at the time of the maximum. Moreover, the Moon will not be a problem for observers as it will be nearly new.
 
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diagrama de la intercepció del rastre de 1932
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diagrama de la intercepció del rastre de 1932
  Diagram from David Asher (Armagh Observatory), where the interception of the trace left behind by the comet Tempel-Tuttle in 1932 is shown. This trail is the cause of this maximum.

There are different forecasts concerning the intensity of the maximum:

The intensity of a meteor shower is measured using the ZHR (zenithal hourly rate); i.e., the average number of shower meteors an observer can see during one hour when its radiant is directly overhead and stars to 6.5 limiting magnitude are visible. From this measure, only the most exceptional showers arrive to ZHR=1000 and they are then called "storms".

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Day Hour ( UT) ZHR Year of the trace
Radiant
RA Decl.
17/1114:34~10/15tradicional*153.6º+21.8º
19/114:4535(Maslov)
120(Asher)
1932154.3º+21.1º
20/117:55Unlikely1366------
21/111:24unlikely1201------
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Day Hour ( UT) ZHR Year of the trace
Radiant
RA Decl.
17/1114:34~10/15tradicional*153.6º+21.8º
19/114:4535(Maslov)
120(Asher)
1932154.3º+21.1º
20/117:55Unlikely1366------
21/111:24unlikely1201------
  * Name given to the interception by the Earth, in its translation movement, of the nominal orbit of the comet.
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 As seen in the table above, there will be some other peaks of intensity, although much fainter. Moreover, the "traditional maximum", observed nearly every year, and corresponding to the peak on 17th November, will not be visible from Europe. It will be only visible from America and, especially, from the northern half of this continent.

Conclusions

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In spite of the existence of several intensity peaks, only the one on 19th November at 4:45 UT is expected to be at once observable and remarkable from western Europe. It will not be a very intense maximum, and the more or less luminous shooting stars (depending on the particular forecast), will not be too bright. It is necessary to find appropiate dark places for astronomical observation. Fortunatelly, the waning Moon will be very close to new and will not give any problem.
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In spite of the existence of several intensity peaks, only the one on 19th November at 4:45 UT is expected to be at once observable and remarkable from western Europe. It will not be a very intense maximum, and the more or less luminous shooting stars (depending on the particular forecast), will not be too bright. It is necessary to find appropiate dark places for astronomical observation. Fortunatelly, the waning Moon will be very close to new and will not give any problem.
 

Related links:

Links to related pages, including the forecasts mentioned above:

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Revision 109 Nov 2010 - SurinyeOlarte

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META TOPICPARENT name="AgendaAstronomica2006En"
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Català Castellano English

Leonids 2006

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(14th to 21st November 2006)

By Víctor Gómez and Eduard Masana

General information:

The Leonids are one of the most classical and popular among meteor showers. Serviastro offers information from published forecasts for this year's shower.

If you want to know more about meteor showers in general, not only Leonids, please check the articles Serviastro prepared about the most remarkable meteor showers in 2005:

  1. Leonids 2005?
  2. Perseids 2005?

2006 Forecast:

Traditionally, the Leonids are a very variable phenomenon; quite different from year to year. That is the reason for the substantial disagreements among the different predictions.

Visió de la Terra que tindran les Leònides en el moment del màxim de la matinada del 19 de novembre

The Earth as seen from coming Leonid meteors at the moment of maximum from 1932 trail at 4:55 UT on 19th November. Red line shows the border of hemisphere where the Moon is above horizon. Image from Maslov.

The increment of meteor's activity will last for a week, however the most important maximum visible this year will happen during the early morning of the 19th November, at approximately 4:45 UT, (allow 5 minutes margin deriving from models). This maximum will be produced by the trace left behind by comet Tempel-Tuttle in 1932. Observers from western Europe will be the best situated since the radiant (the point from which shooting stars seem to come; Leo constellation in this case) will be near the zenith at the time of the maximum. Moreover, the Moon will not be a problem for observers as it will be nearly new.

diagrama de la intercepció del rastre de 1932

Diagram from David Asher (Armagh Observatory), where the interception of the trace left behind by the comet Tempel-Tuttle in 1932 is shown. This trail is the cause of this maximum.

There are different forecasts concerning the intensity of the maximum:

The intensity of a meteor shower is measured using the ZHR (zenithal hourly rate); i.e., the average number of shower meteors an observer can see during one hour when its radiant is directly overhead and stars to 6.5 limiting magnitude are visible. From this measure, only the most exceptional showers arrive to ZHR=1000 and they are then called "storms".

Day Hour ( UT) ZHR Year of the trace
Radiant
RA Decl.
17/1114:34~10/15tradicional*153.6º+21.8º
19/114:4535(Maslov)
120(Asher)
1932154.3º+21.1º
20/117:55Unlikely1366------
21/111:24unlikely1201------

* Name given to the interception by the Earth, in its translation movement, of the nominal orbit of the comet.

Predictions for the Leonids in 2006 are very different from those of a storm, however it seems that it will be eye-naked visible. The most optimistic predictions, proposed by McNaught and Asher in 1999 and partially supported by Mikiya Sato, give a ZHR=120 approximately,and a sharp peak (short duration). Others, in contrast, reduce this value to ZHR=100 (Vaubaillon), or even to ZHR=35 (Maslov).

These important desagreements are a result of different factors, two of which deserve mention: the different forecasting methods and, more importantly, the different measurements of the meteorits causing the peak. The decrease in the value of ZHR proposed by some experts is not due to a smaller concentration of particles in the intercepted trace, but to a smaller size of the meteors.

In any case, meteors considered are of relatively small sizes, impliying that not very bright shooting stars are expected. In fact, Maslov stated that the average magnitude will be between 4 and 5. Experts insist in the need of good observational conditions to enjoy the sight, drawing special attention on atmospheric and light pollution that can hamper the observation.

As seen in the table above, there will be some other peaks of intensity, although much fainter. Moreover, the "traditional maximum", observed nearly every year, and corresponding to the peak on 17th November, will not be visible from Europe. It will be only visible from America and, especially, from the northern half of this continent.

Conclusions

In spite of the existence of several intensity peaks, only the one on 19th November at 4:45 UT is expected to be at once observable and remarkable from western Europe. It will not be a very intense maximum, and the more or less luminous shooting stars (depending on the particular forecast), will not be too bright. It is necessary to find appropiate dark places for astronomical observation. Fortunatelly, the waning Moon will be very close to new and will not give any problem.

Related links:

Links to related pages, including the forecasts mentioned above:

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