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Stephane
登録日: 2008.10.12 記事: 92
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日時: Wed Feb 18, 2009 3:47 am 記事の件名: Magnitude given by UFOANalyzer |
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Hi Sonotaco,
My camera has detected a meteor but UFOAnalzer has some issues to analyse it and to give a correcte magnitude (mag parameter). In this picture, the software give mag=-3.65 and you can see that the value must be higher.
The UFOAnalyser considere this meteor as some multi meteor too. Could you indicate me how I can "forced" the software to analyse only one meteor?
Thanks and kind regards.
Stephane
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SonotaCo Site Admin
登録日: 2004.08.07 記事: 12669 所在地: 139.67E 35.65N
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日時: Wed Feb 18, 2009 11:25 am 記事の件名: Re: Magnitude given by UFOANalyzer |
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Hi Stephane
Wow, big fireball . Great capture
Yes, it seems much brighter.
Because UFOAnalyzer is optimized for the normal meteors,(fainter than mag -3),
there may be many cases that trajectory is divided to multiple parts or magnitude could not be measured properly if a meteor has big or un-continuous luminescence.
The "force" method or tool for manual modification of results is not implemented.
Yet there is no fixed way, there are some methods that possibly improve the result.
1. Tuning of "leap" parameter in Profile/Analyze sheet
It is the threshold of gap length in pixels.
The increase of "leap" will connect the separated trajectories to one, but
it also increases the possibility of wrong connection of noises or other objects.
Try to set leap = 100 or 200 if one trajectory was divided into multiple parts.
2. Tuning of "ddl", "f1","f2" parameter in Profile/Analyze sheet.
3. Manual editing of mask image.
It depends on the case.
Could you show me the snap shot image that shows the measurement status.
You can get by following steps on UFOAnalyzerV2.
1. Check ON "mg" and "lin" check box in Mask Editor sheer.
2. Click "A" button in Main sheet.
3. Push "save" button on Mask Editor sheet.
----> Snap shot image will be save in "Doc" directory.
4. Select other object (other part of the trajectory) in the object list
(middle list in main sheet) and push "save" in Mask Editor sheet.
(rename of image is needed).
If you want it, I can try it. I will prepare temporal ftp server account for you to receive your clip files. Shall I?
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Stephane
登録日: 2008.10.12 記事: 92
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日時: Thu Feb 19, 2009 3:54 am 記事の件名: |
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Hi Sonotaco,
Thanks for your answer.
The leap at 200 give -5.85 of mag. But the clasd of meteor is reconized llike "curve!"
I can send you, via ftp, the files of capture (~150Mo). Could you give me the data for ftp?
Thanks
Best regards.
Stephane
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SonotaCo Site Admin
登録日: 2004.08.07 記事: 12669 所在地: 139.67E 35.65N
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日時: Thu Feb 19, 2009 9:27 am 記事の件名: |
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Stephane wrote: | The leap at 200 give -5.85 of mag. But the clasd of meteor is reconized llike "curve!"
I can send you, via ftp, the files of capture (~150Mo). Could you give me the data for ftp?
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OK, wait for a while.
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SonotaCo Site Admin
登録日: 2004.08.07 記事: 12669 所在地: 139.67E 35.65N
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日時: Fri Feb 20, 2009 11:22 am 記事の件名: |
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Hi Stephane
Thank you for sending. Here is the my analysis result.
You may be able to get one meteor trajectory by setting below.
Profile/Analyze sheet: ddl = 7, leap = 200, f1 = -1, f2 = -1
Class sheet : type param curve > 0.30 deg
About magnitude, -5.65 was measured.
It seems a bit fainter than visual impression.
There were 63 reference stars and they showed good linearity in log scale.
But there are many ground lights and some clouds around the trajectory,
also the brightness was saturated at many pixels.
Therefore there may be larger errors than usual. Mag -7 may be appropriate.
Trail map shows the observed trajectory.
It comes from anti-hellion direction. May be one of them.
But from the radiant estimation by observed velocity changing curve,
the radiant was computed almost ra=150deg(10hour) dec=60deg.
It might be possible.
Ground map was drawn under the assumption of altitude.
It is a result of H1=100km, H2=50km assumption.
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Stephane
登録日: 2008.10.12 記事: 92
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日時: Fri Feb 20, 2009 3:34 pm 記事の件名: |
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Hi SonotaCo,
Thanks for your analyse.
About light ground, this indicate that all magnitudes measured (on this detection and all detections in the pass) are wrong?
Best regards.
Stephane
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SonotaCo Site Admin
登録日: 2004.08.07 記事: 12669 所在地: 139.67E 35.65N
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日時: Fri Feb 20, 2009 6:40 pm 記事の件名: |
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Stephane wrote: | About light ground, this indicate that all magnitudes measured (on this detection and all detections in the pass) are wrong? |
The mag -5.65 was the magnitude of the brightest field of video (1/50sec).
Not the sum or average of the pass. It is the peak.
The magnitude of one field is computed from light sum of the pexels of the object in one field.
Light sum is the sum of the increased_light of pixels of the object.
increaded_light = brightness_of_the_pixel_at_the_instance - brightness_of_the_pixel_before_the_appearance_of_the_object.
Therefore if the darkness of the background is not constant, and the background of fixed stars are dark, and the object appeared on the brighter area, the magnitude becomes a bit fainter.
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