SHG focus improvement : now all wavelenght!

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DSobserver
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SHG focus improvement : now all wavelenght!

Post by DSobserver » Mon May 11, 2015 9:46 pm

Holiday, sunny day, SHG day!

Following yesterday trial, I could detect some collimation focusing issues.

Looks that now it's much better :)

Ha
Image
Cak
Image

Bit more exotic Hb : strange that the big prom at 3 o'clock is here invisable....
Image

Not that much proms todays, so I try surface He shot too! I'm bit surprise with the results : any idea about those dark area at 11 o'clock that I could saw during acquisition?
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Re: SHG focus improvement : now all wavelenght!

Post by Derek Klepp » Mon May 11, 2015 9:57 pm

Great results

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Re: SHG focus improvement : now all wavelenght!

Post by swisswalter » Tue May 12, 2015 4:22 am

Hi Vincent

great job, the sharpness has improved
Only stardust in the wind, some fine and some less fine scopes, filters and adapters as well. Switzerland 47 N, 9 E, in the heart of EUROPE :)

from 7 am - 7 pm http://www.nanosys.ch

from 7.01 pm - 6.59 am http://www.wastronomiko.com some times vice versa ;)

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Re: SHG focus improvement : now all wavelenght!

Post by marktownley » Tue May 12, 2015 5:22 am

Excellent indeed! Very nice :)
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Re: SHG focus improvement : now all wavelenght!

Post by Montana » Tue May 12, 2015 11:43 am

Excellent quality imaging :bow :bow :hamster: no idea about the dark patches though.

Alexandra

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Re: SHG focus improvement : now all wavelenght!

Post by DSobserver » Tue May 12, 2015 3:59 pm

according to daystar, features visible in D3 are: Sunspot Detail, SuperGranulation, Plague, Emission in Flare Footprints, Absorption following Magnetic Lines and small prominences.

Indeed when you check yesterday soho EIT304 who's shows the structure of the Sun's magnetic field you get same areas!

here the modified yesterday picture :

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Re: SHG focus improvement : now all wavelenght!

Post by alex » Wed May 13, 2015 11:04 am

Amazing results!

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Re: SHG focus improvement : now all wavelenght!

Post by p_zetner » Thu May 14, 2015 4:01 pm

Nice results, Vincent. Congratulations on getting your instrument operational.

The black area you see on your He D3 image is indeed real and a feature of the Sun in HeD3 light. You should rotate your disks into the proper orientation for proper discussion about where the features lie.

The He I D3 Line is somewhat of a favourite of mine!

Here are some of the facts I'm familiar with.
Line Centre: 5875.7 Angstroms.
Linewidth in absorption features (plage regions) is ~ 0.5 Angstroms fwhm.

This line is generally invisible on the solar disk (absorption is too weak) except in regions of plage and filaments where absorption is enhanced. The correlation between He absorption features and H alpha features can be seen in the spectroheliograms I posted here in July 2014:

http://solarchat.natca.net/viewtopic.php?f=8&t=12392

The line is very bright at the limb and in prominences. There is a bright D3 limb "band" visible in telescopes with very high angular resolution. Measurements show that this band corresponds to He D3 emission from a shell with a sharply defined lower edge about 1400km above the photosphere.

The mechanism of He D3 absorption is interesting (to me!). Extreme ultraviolet (EUV) radiation from the corona shines downward, illuminating the He from above. This EUV light is energetic enough to ionize the He. Recombination of the ions and free electrons then produces neutral He in excited states of high excitation energy (~20eV) from which we see absorption at the D3 line as well as the He IR (10830 Angstroms) line. The observed shell in limb emission is consistent with this idea. The bottom of the shell corresponds to the maximum depth that the coronal EUV radiation can penetrate (downwards). Also, because radiation from the corona is required, He D3 absorption features don't appear where coronal holes are present. He IR images are used as "proxy" maps of coronal holes, the only tool to map coronal holes from the ground. I guess He D3 images could serve the same purpose but the D3 absorption is much weaker than the IR absorption. Here is a comparison of one of my He D3 images with a professional He 10830A IR image:

http://solarchat.natca.net/viewtopic.php?f=8&t=11761

As opposed to other chromospheric gases, He is optically thin and can be used (in emission, at the limb) to measure chromospheric magnetic fields by a phenomenon called the Hanle effect. The Hanle effect is responsive to much weaker fields than the Zeeman effect and such measurements have given the first accurate picture of chromospheric magnetic fields.

Finally, the D3 line has also been used as a diagnostic of solar flare dynamics. The additional information this line provides is of great interest to the experts but beyond my understanding, at the moment.

Cheers.
Peter.

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Re: SHG focus improvement : now all wavelenght!

Post by Wah » Thu May 14, 2015 5:29 pm

:hamster: :hamster: :hamster:

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Re: SHG focus improvement : now all wavelenght!

Post by marktownley » Thu May 14, 2015 6:21 pm

Fascinating addition of insight Peter, thanks :)
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Re: SHG focus improvement : now all wavelenght!

Post by swisswalter » Thu May 14, 2015 6:33 pm

Hi Peter

thank you so much for the detailed insight information
Only stardust in the wind, some fine and some less fine scopes, filters and adapters as well. Switzerland 47 N, 9 E, in the heart of EUROPE :)

from 7 am - 7 pm http://www.nanosys.ch

from 7.01 pm - 6.59 am http://www.wastronomiko.com some times vice versa ;)

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Re: SHG focus improvement : now all wavelenght!

Post by Montana » Fri May 15, 2015 11:03 am

:hamster: :hamster: thanks for that fascinating description Peter, now we know what the dark patches are :hamster:

Alexandra

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