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Fireball Spectrum
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前田



登録日: 2004.09.01
記事: 2325
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: 176
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.



m20191020_195840_ukkilwinning_p_stretched_Orders.jpg
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m20191020_195840_ukkilwinning_p_stretched_Orders.jpg



20191020_195840_1st_order_annot.png
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20191020_195840_1st_order_annot.png


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Martin Dubs



登録日: 2014.03.04
記事: 54

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: 2325
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: 54

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: 2325
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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