SonotaCo.JP

[前田]

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

[Bill W]

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.

[Martin Dubs]

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

[前田]

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

[Martin Dubs]

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

[前田]

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

[Bill W]

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!

cheers,
Bill.

[Martin Dubs]

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

[SonotaCo]

[Bill W]

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.

[Bill W]

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

[ts007]

Hi bill

This is the spectrum of an iron meteor.

Takashi Sekiguchi

[Bill W]

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

[前田]

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

[Bill W]

WOW, those are spectacular spectra Koji!
Really detailed in the 2nd order.

With a new job and poor weather I have not had much time for observing.

However I did get treated to several clear nights during both the Persied and Geminid meteor showers.

I can't believe time is going by so fast.

This is probably my best Geminid. I was lucky and caught over 20 spectra over the peak nights. The spectrum image is is a single 40ms section from the composite image.

The Mg lines in both the near UV and Green saturated the detector.

(I put a short time lapse video on Youtube from my wide field camera of the Perseid "Peak Nights" too https://youtu.be/AP0900JIySA )

Best Regards,
Bill.