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前田
登録日: 2004.09.01 記事: 2759 所在地: Miyazai JAPAN (E131.4, N31.8)
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日時: Fri Aug 23, 2019 11:41 pm 記事の件名: |
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Hi Bill,
Thank you for posting a nice spectrum.
These are wonderful spectra from blue to purple.
I am amazed at the very good focus from purple to green.
What lenses are used in your system?
How many spectra can the system take for example in July?
Hi Martin,
It's a interesting workshop. I am also surprised by the large number of participants.
Unfortunately, there are no such workshops in Japan.
I would definitely participate if I was close.
In this year it has been bad sky during the Perseid shower and I couldn't get a good spectrum.
Best regards,
Koji
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DMK33GX290ecs + 4mmF1.2 with 600 grooves/mm grating , 30fps
This is the best shot Perseid shower spectrum in this year. |
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最終編集者 前田 [ Sun Aug 25, 2019 11:08 am ], 編集回数 1 回 |
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Bill W
登録日: 2012.02.13 記事: 182 所在地: Glasgow
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日時: Sat Aug 24, 2019 4:12 am 記事の件名: |
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Hi Koji,
Yes!, I am very pleased with the results. The lens I use is a Computar 25mm f1.3 that I found on ebay.
As for numbers I only have captured 2 spectra since I bought the ZWO camera! (I've posted both on this thread.)
Very poor weather (normal for Scotland!) and a small field of view combine to limit numbers but the only way to see detailed spectra is to use longer focal length lenses.
You learn to have patience and enjoy the results when they arrive.
Regards,
Bill.
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前田
登録日: 2004.09.01 記事: 2759 所在地: Miyazai JAPAN (E131.4, N31.8)
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日時: Sun Aug 25, 2019 11:24 am 記事の件名: |
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Hi Bill,
Thank you for your reply.
Your strategy was aiming for a few chance with a long focal length lens. I think it's a great way for automatic observation.
I would like to plan observations with reference to your method.
Best regards,
Koji
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ts007
登録日: 2004.08.09 記事: 5072 所在地: 埼玉県川越市
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Bill W
登録日: 2012.02.13 記事: 182 所在地: Glasgow
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日時: Tue Sep 03, 2019 5:51 pm 記事の件名: |
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Hi TS,
The results look great but what is interesting is what I call the "blue deficiency" problem.
I've noticed this in MANY spectra, including a LOT of my own. It is a curious phenomena.
I have many spectra that seem to stop at the magnesium line ~517nm, That is, the spectrum shows no, or only a few weak, lines shortward of the magnesium wavelength.
I'm not sure whether this is due to the genuine meteor composition, the lack of blue sensitivity of the camera or a drop in efficiency of the grating in the blue, possibly due to the borosilicate substrate (or maybe a combination of all three!)
Testing out my new ZWO cameras with cheap plastic grating film seems to show a dramatic improvement in blue performance. This can be seen in my high res spec with the strength of the CaII lines. (BUT with only two examples so far I don't know how representative this is as they were both intrinsically bright at ~mag -4.)
So, again, I don't know if its a combination of the same three issues or whether the plastic grating film really is a better performer in the blue.
I have now swapped out half of my gratings. I now have three plastic film (~500 lines/mm) and three glass gratings (2 x 600 lines/mm and 1 x 830 lines/mm) on my regular camera array. It will be interesting to see how they compare over the next season. If the cloud ever goes away : - (
Cheers,
Bill.
PS Something else that has occurred to me.... Looking at the results here and at my own spectra, it appears that the effect is most noticeable on spectra taken with 600 lines/mm gratings. I have no idea whether this is a coincidence or not because there are a few with strong CaII lines. The majority do seem to lack blue lines...
There is also a polarisation dependence on grating efficiency but as far as I know meteor light is not (strongly, if at all) polarised.
Perhaps it's an observer bias!, as old photographic methods were a lot more sensitive to blue light....
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ts007
登録日: 2004.08.09 記事: 5072 所在地: 埼玉県川越市
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日時: Sat Sep 14, 2019 12:05 pm 記事の件名: |
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Hi Bill and all
Thank you for your reply.
I think that the way the spectrum appears is due to the camera and the composition and emission of meteors. Even in my case, O, N, Si, and Ca appear frequently at high speed with bright meteors. We found that there are various types of meteor showers.
By the way, the analysis of the spectrum was completed until August after the preparation of the previous material. About 740 triangular graphs and 700 orbits are required. For the time being, I updated the triangular graph.
You can see it at: http://sonotaco.jp/forum/viewtopic.php?p=54153#54153
Contrast with the previous document. In the middle are Per and Cap.
In the future, other graphs from the previous document will be created.
I will continue to do my best in observation and analysis.
ts007
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Bill W
登録日: 2012.02.13 記事: 182 所在地: Glasgow
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日時: Mon Sep 16, 2019 10:47 pm 記事の件名: |
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Hi TS
That is a large number of spectra you have observed, well done!
Another thing I have found with the inexpensive plastic grating material is that it is a lot more transparent than the much thicker glass gratings.
I am now detecting more regular meteors (without spectra) and I can see many more background (reference) stars.
Regards,
Bill.
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ts007
登録日: 2004.08.09 記事: 5072 所在地: 埼玉県川越市
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日時: Tue Sep 17, 2019 6:54 am 記事の件名: |
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Hi Bill
thank you for your comment. I also use a transmissive blazed grating and a transmissive film diffraction grating,
but the film has a larger number of background stars to be removed. However,
the number of spectrum shots is the opposite, and more blazed shots and better resolution,
so two blazed and six films. Both meteor numbers and spectrum numbers are working. Since there is data of sonotaco net,
I got a lot of orbits. I would like to continue observations with this system.
ts007
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Bill W
登録日: 2012.02.13 記事: 182 所在地: Glasgow
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Bill W
登録日: 2012.02.13 記事: 182 所在地: Glasgow
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日時: Thu Oct 24, 2019 7:33 pm 記事の件名: |
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Hi,
I have found it impossible, so far, to identify any lines with confidence.
It certainly doesn't look like a normal meteor.
I found some spectra of the Hyabusa 1 re-entry and there are some similarities so I believe that this indeed may be a piece of space debris.
There don't seem to be many spectra of man made debris re-entering so it's an unusual catch!
Cheers,
Bill.
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前田
登録日: 2004.09.01 記事: 2759 所在地: Miyazai JAPAN (E131.4, N31.8)
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日時: Sun Oct 27, 2019 8:29 pm 記事の件名: |
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Hi Bill,
Thank you for your interesting spectrum.
It seems that the Fe lines appear, but I don't understand either.
If it is an artificial object, it may be judged by the Vg or apparent angular velocity. I hope that simultaneous observations will be obtained.
Regards,
Koji
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Bill W
登録日: 2012.02.13 記事: 182 所在地: Glasgow
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日時: Tue Oct 29, 2019 6:36 pm 記事の件名: |
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Hi Koji,
Can you post a graph or a picture with the Fe lines you have identified?
The NIST database has well over 2000 lines in the 350-450nm range. I can only get some to match then others don't.
Thanks for your help.
Regards,
Bill.
PS Only one other observation seems to have been made. This was on an all sky camera system and shows a bright green meteor . So far there have been no others that could be used to determine an orbit.
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前田
登録日: 2004.09.01 記事: 2759 所在地: Miyazai JAPAN (E131.4, N31.8)
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日時: Tue Oct 29, 2019 11:34 pm 記事の件名: |
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Hi Bill,
Yes, of course.
I also tried to identify the lines, but they didn't match very well. My first impression may have been wrong.
Regards,
Koji
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Bill W
登録日: 2012.02.13 記事: 182 所在地: Glasgow
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日時: Fri Nov 08, 2019 5:39 pm 記事の件名: |
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Hi,
I have to concede defeat! Can't make any sense of this one at all.
So it's #2 in my "UM" files!
cheers,
Bill.
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Bill W
登録日: 2012.02.13 記事: 182 所在地: Glasgow
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日時: Tue Nov 12, 2019 8:01 am 記事の件名: |
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Hi,
Another week another fireball...!
Was reviewing my results from last week when I discovered I had captured another good spectrum.
At least I know what I'm looking at this time!
Appears to be a pure Fe meteor.
Captured with the ZWO 174 camera, 25mm f1.3 lens and a 600lpm fused silica UV grating.
Around 0.34nm/pixel.
cheers,
Bill.
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