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Transit of Mercury in the Spicule Layer. Phil took this great image with his Quantum 6 Scope, Solar Spectrum etalon and PGR Camera.

Welcome to Solar Chat! The best forum for Solar Astronomy
Moving forward from solar cycle 24 to 25

Search found 564 matches

by christian viladrich
Wed Nov 13, 2019 8:08 pm
Forum: This is SolarChat !!
Topic: Mercury Transit
Replies: 11
Views: 172

Re: Mercury Transit

Well done !
by christian viladrich
Wed Nov 13, 2019 8:07 pm
Forum: This is SolarChat !!
Topic: Mercury transit and proms
Replies: 16
Views: 218

Re: Mercury transit and proms

Excellent indeed, congratulations !
by christian viladrich
Wed Nov 13, 2019 8:06 pm
Forum: This is SolarChat !!
Topic: Mercury Solar transit 11th of November 2019.
Replies: 13
Views: 166

Re: Mercury Solar transit 11th of November 2019.

Beautifull images Eric, well done !
by christian viladrich
Tue Nov 12, 2019 7:58 pm
Forum: This is SolarChat !!
Topic: Autostakkert2 flats issue
Replies: 8
Views: 172

Re: Autostakkert2 flats issue

The flat image is to be calculated by AS.
So, first record the flat as an AVI (or SER) file.
Then process this AVI or SER file in AS to calculate the flat image (PNG or TIF).
Then use this flat image in AS.
by christian viladrich
Sat Nov 09, 2019 7:16 pm
Forum: Solar Scope Modifications
Topic: PST mod on a C14
Replies: 11
Views: 602

Re: PST mod on a C14

It would also need large pixel size and / or a focal reducer after the etalon. Otherwise, the image scale would be way too large.
by christian viladrich
Fri Nov 08, 2019 1:39 pm
Forum: Solar Scope Modifications
Topic: PST mod on a C14
Replies: 11
Views: 602

Re: PST mod on a C14

Here is the sweet spot radius depending on the max CWL allowed and on the focal length of the telescope:
Image
by christian viladrich
Fri Nov 08, 2019 1:13 pm
Forum: Solar Scope Modifications
Topic: PST mod on a C14
Replies: 11
Views: 602

Re: PST mod on a C14

Indeed,in a telecentric system: - F/30 and above is "good" with mica-spaced etalons: http://astrosurf.com/viladrich/astro/instrument/solar/FWHM-N.JPG - F/50 and above is needed for air-spaced etalons : http://astrosurf.com/viladrich/astro/instrument/solar/Fig7.82-air-spaced-etalon-FWHM-FD.jpg In a c...
by christian viladrich
Mon Oct 14, 2019 9:19 pm
Forum: Commercial Solar Filters/Cameras/Hardware
Topic: Strehl ratio for a Celestron C11
Replies: 7
Views: 306

Re: Strehl ratio for a Celestron C11

What aperture did you use to take this image ?
by christian viladrich
Mon Oct 14, 2019 6:36 pm
Forum: Commercial Solar Filters/Cameras/Hardware
Topic: Strehl ratio for a Celestron C11
Replies: 7
Views: 306

Re: Strehl ratio for a Celestron C11

Here are some actual interferometric measurements (HASO) of the Strelh ratio of various C11 OTA (EdgeHD or not) at 473 nm : https://www.airylab.com/contenu/mesures/astro/rapport%202015-35003-a.pdf https://www.airylab.com/contenu/mesures/astro/rapport%202012-33001.pdf https://www.airylab.com/contenu/...
by christian viladrich
Tue Sep 17, 2019 8:14 am
Forum: Commercial Solar Filters/Cameras/Hardware
Topic: What do you think is the most versatile high resolution solar telescope design?
Replies: 43
Views: 2741

Re: What do you think is the most versatile high resolution solar telescope design?

Hello Valery, Going back to the initial question of this post, and after the tests recently done à St Véran, I agree that the combination of a large ERF and a reflecting telescope is the best HR solar telescope in large diameter. The Cassegrain configuration is indeed very attractive. Best regards C...
by christian viladrich
Mon Sep 16, 2019 4:43 pm
Forum: Commercial Solar Filters/Cameras/Hardware
Topic: What do you think is the most versatile high resolution solar telescope design?
Replies: 43
Views: 2741

Re: What do you think is the most versatile high resolution solar telescope design?

Hi, I would like to go back to the question of spherochromatism which is inherent to the Schmidt- Cassegrain design. As I have already said, this is nothing new, optics beeing optics. Let's see what Celestron wrote in their White Paper : https://s3.amazonaws.com/celestron-site-support-files/support_...
by christian viladrich
Sun Sep 15, 2019 2:12 pm
Forum: This is SolarChat !!
Topic: H-alpha 31 august, 7 inch Intes, reflections and a BF30.
Replies: 15
Views: 619

Re: H-alpha 31 august, 7 inch Intes, reflections and a BF30.

Hello Bart,
This is a quite good image. Getting rid of these reflections is quite tricky. Keep us posted !
Christian
by christian viladrich
Sun Sep 15, 2019 11:54 am
Forum: Commercial Solar Filters/Cameras/Hardware
Topic: What do you think is the most versatile high resolution solar telescope design?
Replies: 43
Views: 2741

Re: What do you think is the most versatile high resolution solar telescope design?

Hello langleif2, Spherochromatism in Schmidt-Cassegrain is nothing new. You can open any good books on telescope optics to get some information on it. This is just basic optics. You can read for example the two books I co-authored with some friends (unfortunately in French language for now) ;-) Ther...
by christian viladrich
Sun Sep 15, 2019 11:24 am
Forum: Solar Scope Modifications
Topic: A big solar newton for ultra narrowband imaging, possible?
Replies: 30
Views: 1259

Re: A big solar newton for ultra narrowband imaging, possible?

I also have the TS concenter. It is indeed quite good to align the secondary mirror of the 300 mm solar Newtonian.
by christian viladrich
Sun Sep 15, 2019 11:23 am
Forum: Solar Scope Modifications
Topic: A big solar newton for ultra narrowband imaging, possible?
Replies: 30
Views: 1259

Re: A big solar newton for ultra narrowband imaging, possible?

Hello langleif2, This is a textbook example of loss of information in a communication process : A tells a story to B, which B repeats it to C, etc. After a short while the story becomes quite another story :-) So here the actual story : Every year, we have a solar gathering at Serbannes (France). Ne...
by christian viladrich
Sat Sep 14, 2019 8:04 pm
Forum: Solar Scope Modifications
Topic: Budget scope for visual
Replies: 18
Views: 696

Re: Budget scope for visual

430 nm filters are available at Edmund Optics with 10, 25 and 50 nm FWHM, and also at Andover Optics (2 nm FWHM).
by christian viladrich
Tue Sep 10, 2019 7:11 am
Forum: Solar Scope Modifications
Topic: A big solar newton for ultra narrowband imaging, possible?
Replies: 30
Views: 1259

Re: A big solar newton for ultra narrowband imaging, possible?

Hello lanleif2, thanks for this clarification. I am afraid you were a bit mislead. I know rather well AiryLab and MCM. Alex do so since he is the one you got his 250 mm coated by MCM. So far, this is the larger Newtonian telescope with such a coating on the mirror. This telescope and MCM coating is ...
by christian viladrich
Sun Sep 08, 2019 7:30 pm
Forum: Solar Scope Modifications
Topic: A big solar newton for ultra narrowband imaging, possible?
Replies: 30
Views: 1259

Re: A big solar newton for ultra narrowband imaging, possible?

The DOT is a Gregorian telescope, not a Netwonian. This is a huge difference and explains why a cooled diaphragm can be installed at the primary focus. Remember that in a Gregorian telescope the focus of the primary mirror is in front of the secondary mirror, not behind. This makes thing much easier...
by christian viladrich
Fri Sep 06, 2019 7:14 am
Forum: Solar Scope Modifications
Topic: A big solar newton for ultra narrowband imaging, possible?
Replies: 30
Views: 1259

Re: A big solar newton for ultra narrowband imaging, possible?

We were on top of a mountain, 2930 m altitude. Ambient temperature was from 2°C to about 15°C.
So an increase of 10°C is huge. Basically, a delta of more than 2°C between ambient air and an optical part is detrimental to the seeing.
by christian viladrich
Thu Sep 05, 2019 6:48 pm
Forum: Solar Scope Modifications
Topic: A big solar newton for ultra narrowband imaging, possible?
Replies: 30
Views: 1259

Re: A big solar newton for ultra narrowband imaging, possible?

Unfortunately, these tests proved that this idea was a dead end. For Ca K imaging with my TOA150, the 50 mm internal ERF is 33% of the diameter of the objective. I have no internal turbulence. With the 300 m Newtonian of Alex, the ratio is 16%. Now, we can say this is too low... Maybe, another facto...
by christian viladrich
Fri Aug 30, 2019 8:32 am
Forum: Solar Scope Modifications
Topic: Removing mirror’s coating
Replies: 6
Views: 397

Re: Removing mirror’s coating

Hello STu,
Thanks a lot for your input.
Could you tell us a little bit about the differences between iron perchloride et HCl ? I understood than the first one is less agressive ?
by christian viladrich
Sat Aug 24, 2019 3:34 pm
Forum: This is SolarChat !!
Topic: HR images taken with the N300 on August 21
Replies: 9
Views: 460

Re: HR images taken with the N300 on August 21

Thanks to all :-)
I like the fourth one too !
by christian viladrich
Sat Aug 24, 2019 3:33 pm
Forum: This is SolarChat !!
Topic: 24Aug19 - Some fibrils with C11
Replies: 14
Views: 526

Re: 24Aug19 - Some fibrils with C11

Well done Alfred !
by christian viladrich
Thu Aug 22, 2019 6:06 pm
Forum: This is SolarChat !!
Topic: HR images taken with the N300 on August 21
Replies: 9
Views: 460

HR images taken with the N300 on August 21

The Internet is back at St Véran .. Here is a set of pictures taken on August 21 with the 300 mm Newtonian and the 396-5 nm filter. Let's start with a region close to the Eastern limb, with many faculae and darker areas. http://www.astrosurf.com/viladrich/astro/soleil/wl/2019/21August2019-8h03minUT-...