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Calculation

 
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Stephane



登録日: 2008.10.12
記事: 92

記事日時: Sat Jul 18, 2009 10:49 pm    記事の件名: Calculation 引用付きで返信

Hi Sonotaco,

In UFOAnalyser the lat2 and long2 parameters are almost always equal at 999.
In this way, in UFOAnalyser, what is the equation used in your software to convert the az/ev into long/lat from a long/lat/alt of video station?

Thanks and best regards.

stephane
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SonotaCo
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登録日: 2004.08.07
記事: 12653
所在地: 139.67E 35.65N

記事日時: Sun Jul 19, 2009 8:54 am    記事の件名: Re: Calculation 引用付きで返信

Stephane wrote:
In UFOAnalyser the lat2 and long2 parameters are almost always equal at 999.


It is normal for single station observed sporadic meteors.

In the single station observation, some assumptions such as radiant position and velocity or height are needed to compute the 3D position of the trajectory.
UA2 computes lng2 lat2 only when a meter was classified to one of the catalogued meteor showers, using the radiant position of the catalogue.
In our experience , the variation of H2 is very big, and the assumption of H2 was almost meaningless, so UA2 computes only lng1,lat1 (using assumption of H1 in Uty sheet )for sporadic meteors.

The 3D positions in the result of UA2 are just hint for single station observers. If you want to know the precise positions, do multi station observation using UFOOrbitV2. There is no assumption and is far accurate.
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Stephane



登録日: 2008.10.12
記事: 92

記事日時: Sun Jul 19, 2009 6:47 pm    記事の件名: 引用付きで返信

I used UFOOrbit in order to have lat2 and long2 values but it seems that the software, when the second station is close to the first station (around 5 km) it's not possible to compute these values.
With the second station, we are detected the same meteore but in UFOOrbitV2 doesn't match it and didn't give tne lat2 and long2.

Stephane
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SonotaCo
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登録日: 2004.08.07
記事: 12653
所在地: 139.67E 35.65N

記事日時: Sun Jul 19, 2009 9:22 pm    記事の件名: 引用付きで返信

Stephane wrote:
I used UFOOrbit in order to have lat2 and long2 values but it seems that the software, when the second station is close to the first station (around 5 km) it's not possible to compute these values.
With the second station, we are detected the same meteore but in UFOOrbitV2 doesn't match it and didn't give tne lat2 and long2.

It is reasonable.
UFOOrbitV2 restricts the minim distance of stations. It can be specified by GD in Quality sheet.
Anyway, 5km is too close to compute the meteor position. Normally, 50km to 200km is recommended.
It should be at least 30km, otherwise, cross angle of the triangulation plane will be very small and the result may have huge error.
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Stephane



登録日: 2008.10.12
記事: 92

記事日時: Sun Jul 19, 2009 10:37 pm    記事の件名: 引用付きで返信

Thanks for your answer.

Best regards.

Stephane
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