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Fireball Spectrum
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登録日: 2004.09.01
記事: 2284
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

a7s + 35mm with 600 grooves grating, 4K 30p
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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

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.


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