Mg II in UltraViolet

this is the main message area for anything solar :)
User avatar
Bob Yoesle
Im an EXPERT!
Im an EXPERT!
Posts: 469
Joined: Thu Mar 08, 2012 7:24 pm

Re: Mg II in UltraViolet

Post by Bob Yoesle » Thu Nov 08, 2018 4:47 pm

Hi Valery,

Do you have a transmission plot for the C8 DERF? I also would like to know the physical dimensions, and if it is possible to put a central hole in the filter. I'm considering a re-spaced SCT mod and would prefer to mount the secondary mirror to the DERF if it could be made to replace the corrector...

Your C11 images are very good. but they might be even better with a dedicated 393 nm CSA corrector - seems like it would be doable... you never know for sure until you try ;-)
Diagonally parked in a parallel universe.

Curiosity is the father of knowledge; uncertainty is the mother of wisdom.

Dark-Sky Defenders

christian viladrich
Im an EXPERT!
Im an EXPERT!
Posts: 437
Joined: Sun Jun 14, 2015 4:46 pm
Location: France
Contact:

Re: Mg II in UltraViolet

Post by christian viladrich » Thu Nov 08, 2018 8:08 pm

Hi Bob,
I have done some simulations there for a re-spaced C14 :
http://astrosurf.com/viladrich/astro/in ... -Plate.htm
I can run some more for the C8 if it is helpfull.
Christian
Christian Viladrich
Co-author of "Astronomie Planétaire"
http://www.astroplanetes.com/
Co-author of "Astronomie Solaire"
http://www.astronomiesolaire.com/

User avatar
Bob Yoesle
Im an EXPERT!
Im an EXPERT!
Posts: 469
Joined: Thu Mar 08, 2012 7:24 pm

Re: Mg II in UltraViolet

Post by Bob Yoesle » Fri Nov 09, 2018 4:50 am

Hi Christian,

Thanks you very much - that would be wonderful :-) I have seen your C14 re-spaced write up and have purchased a carbon fiber tube towards the implementation...
Diagonally parked in a parallel universe.

Curiosity is the father of knowledge; uncertainty is the mother of wisdom.

Dark-Sky Defenders

User avatar
TheSkyBurner
Almost There...
Almost There...
Posts: 790
Joined: Sat May 05, 2018 7:55 pm
Contact:

Re: Mg II in UltraViolet

Post by TheSkyBurner » Fri Nov 09, 2018 4:52 am

Bob Yoesle wrote:
Thu Nov 08, 2018 4:47 pm
Hi Valery,

Do you have a transmission plot for the C8 DERF? I also would like to know the physical dimensions, and if it is possible to put a central hole in the filter. I'm considering a re-spaced SCT mod and would prefer to mount the secondary mirror to the DERF if it could be made to replace the corrector...

Your C11 images are very good. but they might be even better with a dedicated 393 nm CSA corrector - seems like it would be doable... you never know for sure until you try ;-)
Jp Brahic's scope seems to be the route to take :) You could easily move the corrector plate if you convert the SCT into a truss ( i guess that would make it an R/C scope because you could fix the primary. If this corrector plate hacking solution is viable to get .95 strehl at 393nm I would immediately jump in to the mirror boat. Carbon fiber might not be suitable because of the heat issues, those tubes are dark as night.

For now, refactors are my solar idol because the increase in cost is exponential with that full size D-erf, Especially on those 350mm mirrors........ Looking at $15,000 without a mount, and without the etalon. Jp. must have a great job !:)
He personally told me that he has purchased a .3A solar spectrum filter and will soon be in solar nirvana .
893ACE07-29CC-40D7-B5F2-6FAD4F466223-561-0000006C4252E79E.JPEG
893ACE07-29CC-40D7-B5F2-6FAD4F466223-561-0000006C4252E79E.JPEG (515.84 KiB) Viewed 312 times

User avatar
TheSkyBurner
Almost There...
Almost There...
Posts: 790
Joined: Sat May 05, 2018 7:55 pm
Contact:

Re: Mg II in UltraViolet

Post by TheSkyBurner » Fri Nov 09, 2018 5:29 am

OUCH! the cost of an 8" carbon fiber tube..... LOL @ how much cheaper aluminum is, crazy world we live in..

Epoxy + fishing string = more money than a mineral pulled from the earth that needs to be excavated and literally baked out of metric tons of stone for 1 lb.

https://dragonplate.com/Large-Carbon-Fiber-Tubes


https://www.ebay.com/itm/ZYLtech-2020-A ... 3324739195


carbon fiber tubes for the c14 pre made. Maybe this guy will custom make the corrector plate system hack for everyone?
http://carbonscopetubes.com/Celestron_Tubes.html

christian viladrich
Im an EXPERT!
Im an EXPERT!
Posts: 437
Joined: Sun Jun 14, 2015 4:46 pm
Location: France
Contact:

Re: Mg II in UltraViolet

Post by christian viladrich » Fri Nov 09, 2018 7:46 pm

Hi Bob,
Is this the C8 or the C8 EdgeHD ?
Christian Viladrich
Co-author of "Astronomie Planétaire"
http://www.astroplanetes.com/
Co-author of "Astronomie Solaire"
http://www.astronomiesolaire.com/

User avatar
Bob Yoesle
Im an EXPERT!
Im an EXPERT!
Posts: 469
Joined: Thu Mar 08, 2012 7:24 pm

Re: Mg II in UltraViolet

Post by Bob Yoesle » Sat Nov 10, 2018 12:27 am

Hi Christian,

It's the standard (not the Edge-HD) C8.

Any chance you could "cook up" a spherical aberration corrector using COTS fused silica len(es) from Edmund, Thor Labs, etc? That seems like it would be an ideal CaK imaging platform and relatively less expensive compared to a custom CaK refractor. I would also possibly be placing the corrector just ahead of a Baader 3x telecentric lens system and CaK module.
Diagonally parked in a parallel universe.

Curiosity is the father of knowledge; uncertainty is the mother of wisdom.

Dark-Sky Defenders

User avatar
TheSkyBurner
Almost There...
Almost There...
Posts: 790
Joined: Sat May 05, 2018 7:55 pm
Contact:

Re: Mg II in UltraViolet

Post by TheSkyBurner » Sat Nov 10, 2018 1:40 am

Bob Yoesle wrote:
Sat Nov 10, 2018 12:27 am
Hi Christian,

It's the standard (not the Edge-HD) C8.

Any chance you could "cook up" a spherical aberration corrector using COTS fused silica len(es) from Edmund, Thor Labs, etc? That seems like it would be an ideal CaK imaging platform and relatively less expensive compared to a custom CaK refractor. I would also possibly be placing the corrector just ahead of a Baader 3x telecentric lens system and CaK module.

I wonder if this would fix anything
https://agenaastro.com/apm-2-inch-1-5x- ... -lens.html

User avatar
Bob Yoesle
Im an EXPERT!
Im an EXPERT!
Posts: 469
Joined: Thu Mar 08, 2012 7:24 pm

Re: Mg II in UltraViolet

Post by Bob Yoesle » Sat Nov 10, 2018 2:35 pm

Without the optical prescriptions of the lens system, it is impossible to know.

The respaced SCT corrector probably does a better job of coma reduction, while I believe a separate system would be required for chromatic spherical aberration correction at 393 nm. For CaK work, the PST filters will be OK at f10, but the the Chromatech filter would likely work better with something like the Badder 3x research telecentric which is stated to be well corrected for 393 nm (in addition to being ideal for H alpha).
Diagonally parked in a parallel universe.

Curiosity is the father of knowledge; uncertainty is the mother of wisdom.

Dark-Sky Defenders

User avatar
Valery
Way More Fun to Share It!!
Way More Fun to Share It!!
Posts: 3044
Joined: Sun Nov 18, 2012 3:13 pm

Re: Mg II in UltraViolet

Post by Valery » Sun Nov 11, 2018 7:32 am

TheSkyBurner wrote:
Fri Nov 09, 2018 4:52 am


Jp Brahic's scope seems to be the route to take :) You could easily move the corrector plate if you convert the SCT into a truss ( i guess that would make it an R/C scope because you could fix the primary. If this corrector plate hacking solution is viable to get .95 strehl at 393nm I would immediately jump in to the mirror boat. Carbon fiber might not be suitable because of the heat issues, those tubes are dark as night.

For now, refactors are my solar idol because the increase in cost is exponential with that full size D-erf, Especially on those 350mm mirrors........ Looking at $15,000 without a mount, and without the etalon. Jp. must have a great job !:)
He personally told me that he has purchased a .3A solar spectrum filter and will soon be in solar nirvana .

893ACE07-29CC-40D7-B5F2-6FAD4F466223-561-0000006C4252E79E.JPEG
1. This is the ARIES 12" DERF two bands filter
2. We sell it 2x less than $15000
3. Jean Pierre's Solar Spectrum 1.5 filter is actually 0.25A

Here is the image with a similar 12" filter I took last summer June 19. We now know what kind of images (I hope for better) we can expect from 12" size instruments. Know well Jean Pierre's skill and his seeing conditions we should expect that he will rise the bar higher.


Valery
Attachments
AR12713-June19-2018-UT06h10m-ARIES-312mm-DERF-C14-QUARK-0,2A-Basler1920.jpg
AR12713-June19-2018-UT06h10m-ARIES-312mm-DERF-C14-QUARK-0,2A-Basler1920.jpg (1.23 MiB) Viewed 227 times
"Solar H alpha activity is the most dynamic and compelling thing you can see in a telescope, so spend accordingly." (c) Bob Yoesle.

Largest full size 185 - 356mm Dielectric Energy Rejection Filters (D-ERF) by ARIES Instruments.

christian viladrich
Im an EXPERT!
Im an EXPERT!
Posts: 437
Joined: Sun Jun 14, 2015 4:46 pm
Location: France
Contact:

Re: Mg II in UltraViolet

Post by christian viladrich » Sun Nov 11, 2018 7:16 pm

Hello Bob,

Here are the simulations for a re-spaced classic C8 :
http://astrosurf.com/viladrich/astro/in ... -Plate.htm

The diffraction limited flat-field increases by a factor of four when the Schmidt plate position is set 230mm ahead its nominal position.
Image

There is no impact on the spherochromatism (= still very bad in near UV).

As for the correction in near UV light, there are several issues :
- the spherical aberration changes rapidely with wavelength below 420 mm. This is why the Strelh ratio drops drastically below 420 mm ;
- in order to design a spherical aberration corrector, we would need to know with good accuracy what is the actual shape of the Schmidt plate ;
- this is why ASH actually measured the Schmidt plate of a C8 to design a Barlow lens for this specific C8.

My guess is that a 200 mm F/8 Newtonian telescope is much more appropriated to high resolution Ca K imaging.

I hope to run some tests in Ha on my 300 mm Newtonian with a sub-aperture ERF. If things go well, the next step will be to make a small aperture Ca K ERF filter.

I still have the option open for a ERM coating on my 300 mm scope. The idea would be to have a coating reflecting red (for Ha) and near UV light (for Ca K).
Christian Viladrich
Co-author of "Astronomie Planétaire"
http://www.astroplanetes.com/
Co-author of "Astronomie Solaire"
http://www.astronomiesolaire.com/

User avatar
krakatoa1883
Im an EXPERT!
Im an EXPERT!
Posts: 334
Joined: Sat Jun 11, 2016 9:41 am
Location: Mediolanum

Re: Mg II in UltraViolet

Post by krakatoa1883 » Sun Nov 11, 2018 8:04 pm

In my opinion for hires imaging in the near UV correcting the system for SA is much more important that enlarging the D-L field, thus an all-reflecting system would definitely be much more preferable than modifying a SCT.

BTW, one can consider a commercial Cassegrain, it is a relatively inexpensive scope that can be modified to make it better suited for solar work.
Raf
My personal page on Google+
My personal web site on practical astronomy and astronomical optics

christian viladrich
Im an EXPERT!
Im an EXPERT!
Posts: 437
Joined: Sun Jun 14, 2015 4:46 pm
Location: France
Contact:

Re: Mg II in UltraViolet

Post by christian viladrich » Sun Nov 11, 2018 8:31 pm

Interesting info Raf :-)
I didn't know they have these small size Cassegrain scopes.They have quartz mirrors which is very nice. I have no idea of the optical quality.
Christian Viladrich
Co-author of "Astronomie Planétaire"
http://www.astroplanetes.com/
Co-author of "Astronomie Solaire"
http://www.astronomiesolaire.com/

george9
Oh, I get it now!
Oh, I get it now!
Posts: 41
Joined: Tue Jan 26, 2016 1:28 am

Re: Mg II in UltraViolet

Post by george9 » Sun Nov 11, 2018 8:56 pm

They also have a 12" classic Cassegrain from Orion Optics UK, although it costs four times as much. 25% obstruction (vs 33% on the smaller ones). Comes with a Ronchi test, but no mention of minimum performance. George

User avatar
Merlin66
Librarian
Librarian
Posts: 3164
Joined: Tue Dec 13, 2011 1:23 pm
Location: St Leonards, Australia
Contact:

Re: Mg II in UltraViolet

Post by Merlin66 » Sun Nov 11, 2018 11:07 pm

Hmmm
Once we have solved all these technical difficulties....
What about a camera which can record that far into the UV??????
"Astronomical Spectroscopy - The Final Frontier" - to boldly go where few amateurs have gone before
https://groups.yahoo.com/neo/groups/ast ... scopy/info
"Astronomical Spectroscopy for Amateurs" and
"Imaging Sunlight - using a digital spectroheliograph" - Springer

User avatar
eroel
Way More Fun to Share It!!
Way More Fun to Share It!!
Posts: 4102
Joined: Mon Dec 19, 2011 10:45 pm
Location: México D.F.

Re: Mg II in UltraViolet

Post by eroel » Mon Nov 12, 2018 12:57 am

Valery:
A good thread with super shots and info.
Best wishes,
Eric.

User avatar
TheSkyBurner
Almost There...
Almost There...
Posts: 790
Joined: Sat May 05, 2018 7:55 pm
Contact:

Re: Mg II in UltraViolet

Post by TheSkyBurner » Mon Nov 12, 2018 5:29 am

Merlin66 wrote:
Sun Nov 11, 2018 11:07 pm
Hmmm
Once we have solved all these technical difficulties....
What about a camera which can record that far into the UV??????
Ken, this part of the challenge is easy! It would be as simple as placing a "scintillation crystal screen" inside of your c-mount just before the imaging sensor..

https://www.crytur.cz/products/scintillation-screens/

These crystals convert soft xray's / UV-c light into higher frequencies specifically for imaging.

User avatar
TheSkyBurner
Almost There...
Almost There...
Posts: 790
Joined: Sat May 05, 2018 7:55 pm
Contact:

Re: Mg II in UltraViolet

Post by TheSkyBurner » Mon Nov 12, 2018 6:59 am

christian viladrich wrote:
Sun Nov 11, 2018 7:16 pm
Hello Bob,

Here are the simulations for a re-spaced classic C8 :
http://astrosurf.com/viladrich/astro/in ... -Plate.htm

The diffraction limited flat-field increases by a factor of four when the Schmidt plate position is set 230mm ahead its nominal position.
Image

There is no impact on the spherochromatism (= still very bad in near UV).

As for the correction in near UV light, there are several issues :
- the spherical aberration changes rapidely with wavelength below 420 mm. This is why the Strelh ratio drops drastically below 420 mm ;
- in order to design a spherical aberration corrector, we would need to know with good accuracy what is the actual shape of the Schmidt plate ;
- this is why ASH actually measured the Schmidt plate of a C8 to design a Barlow lens for this specific C8.

My guess is that a 200 mm F/8 Newtonian telescope is much more appropriated to high resolution Ca K imaging.

I hope to run some tests in Ha on my 300 mm Newtonian with a sub-aperture ERF. If things go well, the next step will be to make a small aperture Ca K ERF filter.

I still have the option open for a ERM coating on my 300 mm scope. The idea would be to have a coating reflecting red (for Ha) and near UV light (for Ca K).

That re-coating idea for your 300mm scope would be phenomenal, i wish this was a standard option for large mirrors and not a custom order. Since so many people are using narrow band filters anyways on these telescopes with filter wheels, it seems only logical to have a mirror with the triband color coating with 10nm bandwidth for each..

Check out the samples from another user with the same coating on his mirror.

viewtopic.php?f=11&t=25081

User avatar
Bob Yoesle
Im an EXPERT!
Im an EXPERT!
Posts: 469
Joined: Thu Mar 08, 2012 7:24 pm

Re: Mg II in UltraViolet

Post by Bob Yoesle » Mon Nov 12, 2018 12:48 pm

" Here are the simulations for a re-spaced classic C8 :
http://astrosurf.com/viladrich/astro/in ... -Plate.htm "

Thanks so much for this Christian!
Diagonally parked in a parallel universe.

Curiosity is the father of knowledge; uncertainty is the mother of wisdom.

Dark-Sky Defenders

Post Reply

Who is online

Users browsing this forum: No registered users and 11 guests