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Fireball Spectrum
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前田



登録日: 2004.09.01
記事: 2547
所在地: Miyazai JAPAN (E131.4, N31.8)

記事日時: Thu Aug 26, 2021 10:19 pm    記事の件名: 引用付きで返信

Hi Bill,

Your camera's gamma could be 0.5.
My camera is made by SONY, so I use ITU709. This standard corresponds to gamma 0.45.
Isn't the gamma of the image converted when analyzing the spectrum?

In my color spectrum, purple is hard to make an image due to the influence of filter in the camera. In rare cases, strong lines may appear near 400 nm but those lines cannot be used for analysis due to be strongly influenced by the image processing in the camera.
For this reason, I am very interested in the spectrum in the purple region.

Last night I got a good-looking spectrum of kappa Cygnids. The light curve is also unique. It was about -3 mag.
The background is very bright due to the near full moon.

Thank you
Koji



M20210826_030523_JPMZ1_HSPtrim.jpg
 説明:
a7s + 35mm with 600 grooves grating, 4K 30p
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M20210826_030523_JPMZ1_HSPtrim.jpg


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Bill W



登録日: 2012.02.13
記事: 180
所在地: Glasgow

記事日時: Thu Sep 02, 2021 1:17 am    記事の件名: 引用付きで返信

Hi,
That's another really beautiful spectrum Koji.

I prefer using the monochrome cameras so that I have access to the entire spectrum. Much detail can be seen the near UV/blue end where many Fe/Mg and the Ca lines are present.

I have had some inspiration!

When I started using the HD cameras and I posted the image from 2019 10 20 I could not understand what I was seeing. But now that I have had some experience with other very high resolution spectra I now know what I'm looking at!

The images now explain the spectrum. All that was wrong was that I had bumped the focus off. Although the spectrum is a bit blurry it is easy to see the main groups.

Also, because the 2nd order is visible it must mean that this was a relatively slow meteor as these line are not overlaid or masked by the bright near IR emissions that come from the atmosphere. That was one of the issues that I think confused me. I was expecting other lines at this part of the image.

Cheers,
Bill.



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Martin Dubs



登録日: 2014.03.04
記事: 56

記事日時: Tue Sep 28, 2021 4:28 am    記事の件名: 引用付きで返信

Hi,

for a while I have not posted here. That does not mean that I have not done anything. I progressed with my Python script for the analysis of meteor spectra. In the meantime I added instrument response and the correction of atmospheric extinction. You find the actual version of the script here:
https://github.com/meteorspectroscopy/meteor-spectrum-calibration
Before trying it out you may look at my blog with a history of the development:
https://meteorspectroscopy.org/2021/09/26/atmospheric-extinction-python-processing/
Here a recently captured spectrum, together with the analysis. You may note that I have upgraded my camera, I use now a TIS DMK 33GX249 with a Kowa LM16HC f: 16mm F/1.4 lens. At the short wavelength side there is some defocusing visible (Ca-lines), but apart from that it is quite an improvement from my earlier Watec camera. Normally these lines are quite weak so I did not notice the defocusing before.
More spectra you can find here:
http://www.meteorastronomie.ch/images/20210630_Meteorspectra.pdf

Clear skies,

Martin



S20210922_040601_MAI_2_1stO.png
 説明:
1st order with annotations
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S20210922_040601_MAI_2_1stO.png



M20210922_040601_MAI_2P.jpg
 説明:
peak image of spectrum

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前田



登録日: 2004.09.01
記事: 2547
所在地: Miyazai JAPAN (E131.4, N31.8)

記事日時: Wed Sep 29, 2021 10:57 pm    記事の件名: 引用付きで返信

Hi Martin,

I haven't forgotten about you.
Thank you for the analysis result of the spectrum by the new camera.

You chose an interesting camera.
I may see the spectrum on the IMX249 for the first time.
Certainly, the lens may change in the future, but the noise of the camera seems to be good.

How dark can your system capture the stars with a grating? I am very interested.


I also saw your new analysis results with great interest.

The meteor, M20210509_023009_MAI_2, has a high proportion of iron, so I think it is likely to be an iron meteor. What do you think of it?

Cheers,
Koji
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Martin Dubs



登録日: 2014.03.04
記事: 56

記事日時: Fri Oct 08, 2021 11:22 pm    記事の件名: 引用付きで返信

Hi Koji,

thank you for your kind reply. To your questions there is no easy answer. Because the weather has been mostly moderate to bad or moonlight, I do not know exactly how sensitive the camera is. I have no comparison with other cameras apart from the Watec with a different focal length, pixel size etc. I have not measured sensitivity or read noise.
In the spectrum I only indicated the calibration lines, but you are right, there are plenty of iron lines as well. The analysis with UFO Orbit shows a fast sporadic meteor with v0 = 53km/sec, this also explains the strong calcium lines.

Regards, Martin
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前田



登録日: 2004.09.01
記事: 2547
所在地: Miyazai JAPAN (E131.4, N31.8)

記事日時: Wed Oct 13, 2021 9:45 pm    記事の件名: 引用付きで返信

Hi Martin,

Thank you for your reply.

The velocity of this meteor (53km / s) seems to be a little too fast for an iron meteor.
However, I thought it was a very interesting meteor with a high rate of iron.

Cheers,
Koji
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Bill W



登録日: 2012.02.13
記事: 180
所在地: Glasgow

記事日時: Fri Nov 26, 2021 8:25 am    記事の件名: 引用付きで返信

Hi All,

Given the low Vg and good fall of meteor within the fov this is an excellent Southern Taurid spectrum.

The Mg and Na lines are saturated. My friends at the NEMETODE group determined the orbit and estimated the mag at -5.4

There are many lines I'm not 100% sure off. This is my best yet! I can't believe the results are still getting better and better...

Very pleased with this one! Shocked Very Happy

cheers,
Bill.



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Martin Dubs



登録日: 2014.03.04
記事: 56

記事日時: Sun Jan 02, 2022 6:49 am    記事の件名: 引用付きで返信

Happy New Year to everybody.

the last year has been quite successful. I finished my Python script for the analysis of spectra (It can be downloaded from https://github.com/meteorspectroscopy/meteor-spectrum-calibration). The latest additions are the use of a flat field to correct for varying sensitivity over the image area, which is especially useful for wide angle lenses. For a description see: https://meteorspectroscopy.org/2021/12/20/creation-and-use-of-flat-field-for-meteor-spectroscopy/
As an example of the spectrum analysis I include a report on the 2021 Geminides recorded at Maienfeld (Geminid spectra 2021). Most notable is the fact that the Na-lines at 589 nm are very weak, in most cases weaker than the Mg-line at 517.5 nm. This has also been noted by others (see e.g. the paper by Kasuga et. al.:
https://www.aanda.org/articles/aa/pdf/2005/29/aahc081.pdf
In case you are interested in more meteor spectra, the complete list for 2021 is available from https://meteorspectroscopy.org/2022/01/01/meteor-spectra-2021/

Clear Skies,

Martin



Geminid spectra 2021.pdf
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Geminid spectra 2021

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SonotaCo
Site Admin


登録日: 2004.08.07
記事: 11972
所在地: 139.67E 35.65N

記事日時: Sun Jan 02, 2022 7:01 am    記事の件名: 引用付きで返信

Bill W wrote:

Given the low Vg and good fall of meteor within the fov this is an excellent Southern Taurid spectrum..

Impressive Exclamation Shocked Surprised
The amaging resolution looks like a indoor experiment.
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Bill W



登録日: 2012.02.13
記事: 180
所在地: Glasgow

記事日時: Mon Jan 17, 2022 2:58 am    記事の件名: 引用付きで返信

Dear SonotaCo,

Firstly a belated happy new year to you and all the forum users.

Thank you, yes, it is an amazing spectrum. I've had a look at some old photographic fireball images taken using very long lenses and large format film and this matches the resolution of these older pictures. These old photographic fireball spectrum images were very rare, maybe once a decade. Now, rather than once a decade I can now capture several of these per year. It's amazing progress, the technology is incredible.
(I'd still like a camera with slightly larger pixels though!)

There are lots of spectra that have higher resolution but over a smaller wavelength range, whereas this covers the entire visible spectrum. This is certainly one of the best meteor spectrum ever taken (so far!). But it would not be possible without your wonderful UFO Capture HD software and other amazing software by Valerie Desnoux and Christian Buil! I have been using this combination since I started in video spectroscopy 14 years ago.

All I do is point the camera at the sky and then frequently curse my cloudy Scottish weather I have to endure. For any of these great results there are MANY MANY other hours of frustration!

Look how far we've come... this is my very first spectrum at 320X240 pixel resolution...

Here's hoping for some more good spectra this year.

Best Regards,

Bill. Shocked



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Bill W



登録日: 2012.02.13
記事: 180
所在地: Glasgow

記事日時: Mon Aug 29, 2022 11:59 pm    記事の件名: Takashi Sekiguchi 引用付きで返信

Hi,
I'm trying to get an email address for Takashi?
Thanks,
Bill.
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ts007



登録日: 2004.08.09
記事: 4424
所在地: 埼玉県

記事日時: Tue Aug 30, 2022 10:29 am    記事の件名: is the address. 引用付きで返信

Hi bill

This is the spectrum of an iron meteor.

Takashi Sekiguchi



M20220730_021904_jpSaitama1_ZaPm.jpg
 説明:
IMX327+6mmF0.95 500gl
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M20220730_021904_jpSaitama1_ZaPm.jpg




最終編集者 ts007 [ Wed Aug 31, 2022 5:12 pm ], 編集回数 1 回
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Bill W



登録日: 2012.02.13
記事: 180
所在地: Glasgow

記事日時: Tue Aug 30, 2022 10:04 pm    記事の件名: 引用付きで返信

Hi Takashi,
Thank you for the info. I have sent you an email.
Regards,
Bill.
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前田



登録日: 2004.09.01
記事: 2547
所在地: Miyazai JAPAN (E131.4, N31.8)

記事日時: Mon Nov 14, 2022 8:18 pm    記事の件名: Taurids fireball 引用付きで返信

Hi all,
This year, as expected, the Southern Taurus shower is very active. There are many bright meteors, especially in the fireball class, so we have been able to capture some spectra.

I also finally caught a fireball on my camera last night, so I can show it to you all.
The two images show the same fireball captured by different cameras.


Regards,
Koji



M20221114_015942_JPMZ1_HSP40p.jpg
 説明:
mag. -3.8, 1.7sec., STA
a7s+35mmF1.4 with 600 grooves grating, 4K 30p
Reduced to 40%
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M20221114_015942_JPMZ1_HSP40p.jpg



M20221114_015942_JPMZ1_HEP40p.jpg
 説明:
a7s+50mmF1.4 with 600 grooves grating, 4K 30p
Reduced to 40%
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