Mg II in UltraViolet

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Mg II in UltraViolet

Post by Valery » Wed Oct 31, 2018 4:30 am

See what can be imaged in near UV light at Mg II line.

https://www.aanda.org/articles/aa/pdf/2 ... 358-15.pdf

And very interesting reading.


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Re: Mg II in UltraViolet

Post by TheSkyBurner » Wed Oct 31, 2018 5:09 am

IRIS is nothing short of the best solar telescope ever created by man :)

I doubt any body will ever beat it, unless someone starts imaging neutrinos.

I wish somebody would mass produce a complete digital spectrohelioscope in a pst body! Something you just plug into any telescope and it scans for you and builds the image for you. Vibrating slit, rotating prism cubes etc.

Its all possible with an arduino kinematic control module, it just needs some great engineering and a probably $50,000 startup costs.

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Re: Mg II in UltraViolet

Post by Montana » Wed Oct 31, 2018 9:57 am

Thanks for the read Valery

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Re: Mg II in UltraViolet

Post by marktownley » Thu Nov 01, 2018 9:48 am

Interesting read indeed!
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Re: Mg II in UltraViolet

Post by Valery » Thu Nov 01, 2018 11:13 am

Note, folks, that even with large(!) CWL shift the picture remains VERY different to what can be seen in a continuum and this makes me optimistic that even 1A two cavity filter will deliver unusual picture full of quite different details. The only problem is do we have such a UV sensitive CCD or CMOS cameras with high speed?

But... even a 120mm telescope will have a resolution of 280mm telescope worked at 656nm Ha !!!

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Re: Mg II in UltraViolet

Post by marktownley » Fri Nov 02, 2018 1:46 pm

How feasible is it as a filter?
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Re: Mg II in UltraViolet

Post by Valery » Fri Nov 02, 2018 4:55 pm

marktownley wrote:
Fri Nov 02, 2018 1:46 pm
How feasible is it as a filter?
We need professional opinion(s).
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Re: Mg II in UltraViolet

Post by TheSkyBurner » Fri Nov 02, 2018 7:13 pm

You dont need opinions, you just need to pay for it.

The light at 280nm hitting the ground is not at its peak value unless the sun is at the zenith..

But as valery said a 100mm scope is like a 280mm scope with its high intensity. So although the value of light is low it is highly intense.

I would offer to dump more of my own personal money into the experiment and just get it done without questions but the ls50c mod is my last projec to conquer , then im gone!

Already getting told what im doing isnt gonna work and is a waste of money, AGAIN.

Valery, get the filter made. I am sure they will tell you its impossible to build to your specifications, until you show them the 25 grand. Then suddenly it will be very easy for the,.

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Re: Mg II in UltraViolet

Post by TheSkyBurner » Fri Nov 02, 2018 8:13 pm

the first challenge you need to face, is finding the quartz objective lens. /you can get these, and they are developed for UV photo-lithography wafer technologies.

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Re: Mg II in UltraViolet

Post by marktownley » Sat Nov 03, 2018 4:55 pm

What is the QE of our cameras at these wavelengths?
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Re: Mg II in UltraViolet

Post by jp-brahic » Tue Nov 06, 2018 10:59 am

thanks for this article Valery :)

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Re: Mg II in UltraViolet

Post by Valery » Tue Nov 06, 2018 4:07 pm

marktownley wrote:
Sat Nov 03, 2018 4:55 pm
What is the QE of our cameras at these wavelengths?
I don't know. But possibly high enough. All in all UV is much more powerful than IR radiation.

But they may be expensive.


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Re: Mg II in UltraViolet

Post by marktownley » Tue Nov 06, 2018 6:23 pm

'Off the Shelf' UV achromats aren't ideal, but could form a starting point for such a scope. You could make a tiny full disk instrument; the 50/200 https://www.edmundoptics.eu/f/near-uv-n ... ses/13900/ could replace the objective in a finder scope, and then mount the filters on the nose of a camera. Would be easy to make up a barlow https://www.edmundoptics.eu/f/UV-Fused- ... ses/12414/ to increase image scale for small pixel camera. Not perfect but could give a cheap indication of success for the idea. Good sky transparency and altitude would increase success.
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Re: Mg II in UltraViolet

Post by Valery » Wed Nov 07, 2018 5:19 am

marktownley wrote:
Tue Nov 06, 2018 6:23 pm
'Off the Shelf' UV achromats aren't ideal, but could form a starting point for such a scope. You could make a tiny full disk instrument; the 50/200 https://www.edmundoptics.eu/f/near-uv-n ... ses/13900/ could replace the objective in a finder scope, and then mount the filters on the nose of a camera. Would be easy to make up a barlow https://www.edmundoptics.eu/f/UV-Fused- ... ses/12414/ to increase image scale for small pixel camera. Not perfect but could give a cheap indication of success for the idea. Good sky transparency and altitude would increase success.
If one will go this way, he should not save money on a too small telescope. 100mm is a minimal size I would say. Minimal SA is a must for such a telescope. A must have also a SSM.
The main price driving factor is an etalon with a 0,5A bandwidth. Give me such an etalon and I will make a telescope without any real problem.
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Re: Mg II in UltraViolet

Post by Bob Yoesle » Wed Nov 07, 2018 4:15 pm

An interesting research paper - thanks for sharing it Valery.

"If one will go this way, he should not save money on a too small telescope. 100mm is a minimal size I would say. Minimal SA is a must for such a telescope. A must have also a SSM. The main price driving factor is an etalon with a 0,5A bandwidth. Give me such an etalon and I will make a telescope without any real problem. "

"The only problem is do we have such a UV sensitive CCD or CMOS cameras with high speed?"

For me a bigger problem would be how well any COTS telescope would perform at this wavelength (280 nm). The only telescope that might do a passable if not good job is the Takahashi TOA 130:

TOA 150 Long CA.jpg
TOA 150 Long CA.jpg (41.82 KiB) Viewed 415 times

A substantial investment in its own right:


http://www.takahashiamerica.com/takahas ... actor.html


I doubt Takahashi knows how well the TOA 130 optics perform at 280 nm, nor do they probably care, so you'll have to buy one to find out.

The MG II on-band images look very similar to H alpha, and for Ellerman Bombs, off-band Ha (and CaK) might be just as suitable:

fg1.h.jpg
fg1.h.jpg (283.97 KiB) Viewed 415 times
Alexandra's CaK Ellerman Bomb series.jpg
Alexandra's CaK Ellerman Bomb series.jpg (196.64 KiB) Viewed 415 times

So what this would actually entail is a very expensive niche filter, for which you would have to have a very expensive telescope optic (if not using a reflector with appropriate ancillary lenses), and an as yet unknown sensitivity CCD/CMOS camera, and so forth.

Honestly, given my already considerable investment in H alpha and CaK, I think I'll pass. In fact, I'd rather put my money towards a dual or tri-band band C8 ERF scope, and a solution for solving the SCA of the C8 at 393 nm so that it could better be used for CaK work:

C8 optical graphs.jpg
C8 optical graphs.jpg (163.21 KiB) Viewed 415 times

Fix that and I'm all in!

Therefore I'll probably leave the the Mg II line for solar researchers who will do more than just take pretty pictures... not that pretty pictures aren't fun to look at - I've taken a few of them myself ;-)
Last edited by Bob Yoesle on Wed Nov 07, 2018 6:04 pm, edited 3 times in total.
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Re: Mg II in UltraViolet

Post by p_zetner » Wed Nov 07, 2018 4:52 pm

Well argued, Bob.

If I could add to this discussion, I would address an even bigger elephant in the room: atmospheric transmission at 280nm.
Here are atmospheric transmission curves at the Paranal VLT site. Paranal is located in the Atacama Desert of northern Chile on Cerro Paranal at 2,635 m altitude!
IMG_2843.jpg
IMG_2843.jpg (352.58 KiB) Viewed 407 times
Transmission rapidly disappears beyond ~ 320nm.

Cheers.
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Re: Mg II in UltraViolet

Post by Bob Yoesle » Wed Nov 07, 2018 5:13 pm

Thanks for that Peter ;-)

OK, so now we add a sounding rocket to the equipment list:

https://www.youtube.com/watch?v=sQw_C5KLhFM

Alternatively, one could always move to Antarctica:

Solar-Spectrum-GballEditz.png
Solar-Spectrum-GballEditz.png (99.12 KiB) Viewed 398 times


https://www.youtube.com/watch?v=fzN0LbZ ... e=youtu.be


But you'll probably also need a new wardrobe for keeping warm... and dew heaters.
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Re: Mg II in UltraViolet

Post by p_zetner » Wed Nov 07, 2018 6:03 pm

Thanks, Bob.

I like the idea of a visit to Antarctica. Living in central Canada with some harsh winter weather, I’m pretty much set for clothing. Can’t forget to slather on the sunscreen with the enhanced UVC !

:-)

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Re: Mg II in UltraViolet

Post by Valery » Wed Nov 07, 2018 6:12 pm

Hi Bob,

Here is the CaK image of the sun active area #12715 taken with 11" SCT. So, I see no problems at all for for a C8. And you can get a DERF filter soon after the order.


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Re: Mg II in UltraViolet

Post by Merlin66 » Wed Nov 07, 2018 11:39 pm

I use various telescopes , including the ol' Genesis for spectroscopy with commercial CCD's.
My experience is that the available CCD's have little or no response below 360nm.
The Strehl ratio for the Genesis at around 370nm seems acceptable, giving a good workable stellar image.
I use the ATiK 314L camera most of the time......
This is the UV spectrum of Sirius taken with the above gear.
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Re: Mg II in UltraViolet

Post by TheSkyBurner » Thu Nov 08, 2018 6:18 am

for what opinions are worth , if anyone does decide to pursue this.

You just need to realize that if you have a 99% transmission etalon you are still going to use an energy rejection and attenuation to control the image brightness at the sensor of any solar telescope.

So, naturally (because of the earths atmosphere) no additional attenuation is required. The earths atmosphere is going to function as your primary energy rejection filter.

Since this is not a visual use system, the attenuation only needs to be sufficient for a sensor. Which, because of the nature of the silicon this also acts as a barrier to the 300nm light.

If anyone can calculate the exact amount of penetrating light hitting the ground at 280nm you can then autoamtically apply this loss in transmission directly to the value passed through the etalon or bandpass. The account for the light lost by the silicon chip.

Finding real fused quartz filters and fused quartz objectives is the hurdle here. Its going to cost a bundle, (pure fluorite crystals would probably used to make the etalon in this instance, and it only has to be 20mm like a pst etalon!). Is it worth having a 20,000$ telescope? Some people are going to say yes because they already own them,. the meade 16" sct for example! The toa-150... the list goes on, telescopes are not cheap.. (ANY astrophysics model....) Randy shivak comes to mind with the $20,000$ istar h-alpha objective he purchased.... Bob: you own that coronado 140mm etalon, that thing cost a few pennies...

Lest you forget the lunt ls232..... https://telescopes.net/store/ls230tha-p ... b3400.html

If you can calculate a transmission of just 5% hitting your sensor, you automatically have success and the ability to record images.

You would also own the only telescope on earth that does narrowband solar imaging at 280nm. (seems like that is worth something right there alone....)

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Re: Mg II in UltraViolet

Post by TheSkyBurner » Thu Nov 08, 2018 6:40 am

Would anybody say that this guy, Harald Paleske wasted his money? ?


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Re: Mg II in UltraViolet

Post by TheSkyBurner » Thu Nov 08, 2018 6:43 am

and here is the company that will make the etalon for you. I hope you find a good translator...

http://www.psitd.com/bbs/board.php?bo_t ... =63&page=4

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Re: Mg II in UltraViolet

Post by TheSkyBurner » Thu Nov 08, 2018 6:58 am

And you know, considering the amount of money that is thrown at education....
Sending a balloon up there 100,000 feet with a solar telescope is actually something HIGH SCHOOL KIDS do every day, no sounding rocket required... It falls to earth unharmed every time and has image stabilizer + gimbals to keep it pointed at the sun. .

I like when people tell me something is impossible....
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http://sunbyte.group.shef.ac.uk/ <------ AIRYLAB h-alpha scope on a balloon.

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Lunt h-alpha pressure tuner on a baloon,.
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Re: Mg II in UltraViolet

Post by Valery » Thu Nov 08, 2018 9:22 am

TheSkyBurner wrote:
Thu Nov 08, 2018 6:40 am
Would anybody say that this guy, Harald Paleske wasted his money? ?
His achievements were high at that time. Now he is working about solar 12" refractor.
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