Spectrohéliographe H-alpha du 8 octobre

[thesmiths 285]

Cette session était similaire à celle du 6 octobre (Spectrohéliographie H-alpha du 6 octobre). Cette fois-ci, j'ai pu utiliser la mise au point électronique ZWO à distance et faire toute la capture d'images depuis l'intérieur.  Je présente ici les versions non inversées et inversées des mêmes données. J'aime bien les images inversées pour l'effet dramatique, et les proéminences semblent mieux ressortir.

 

Below is a stack of the best 17 frames from 26 SER files. The exposure was 2.0ms, gain zero, fps 290, scan rate 13x sidereal. 106mm / 720mm APO refractor, 2400 l/mm grating, 9 micron wide chrome on fused quartz slit, ZWO 183MM camera. October 8, 09:25 UTC to 09:33 UTC.

 

Edited October 8, 2022 by thesmiths

[Jean-Francois P 217]

Hello Douglas,

 

Why do you have all this sunny days in London ?

I have in the south of Germany, rain, fog, rain with fog, fog with rain, ... :-)

Now with the low sun, I could have only a short observation window from my terrasse in the morning between 8:00 and 10:00.

The most of the cases, it was sunny during the week when I must go to work, and it was rain/foggy in the weekend.

 

I find your processing very good balanced. Very nice "ton mapping" on the sun disc. We can see a lot of details without over contrast.

Other point, the transition to the protuberances is very good ... how do you achieved to show the faint protuberances without burning the disc ?

 

Best regards under the fog :-)

Jean-Francois

 

[thesmiths 285]

Dear JFP,

 

Yes, there were a few sunny days for a change and although the viewing time is short, the cooler air is in fact favourable. I have strategically positioned my mount to catch the sun as it passes between two roofs in between around 10:20am and 11:20am. I can set up up everything before that and then get a few good data sets during that one hour viewing window. 

 

Quote

how do you achieve to show the faint protuberances without burning the disc?

 

I found a nice feature in the version of Photoshop that I have. I use the cheapest version called Photoshop Elements -- it is sometimes available by digital download from online stores for a quite low price. I recently got the 2022 version for 40 pounds; the license is useable on two computers simultaneously, e.g. desktop and laptop. There is a nice feature called "Shadows/Highlights" (under 'Enhance' --> 'Adjust Lighting'). A very tiny amount of "Lighten Shadows" (around 1% to 5%) brings out the prominences, and then a moderate amount of "Darken Highlights" (around 5% to 15%) will decrease the brightness at the centre of the disk. It is doing something to make the tone curve non-linear and it definitely works well on the Sun (not so good on deep sky though). The other feature that I play with is under "Levels" (also under 'Enhance' --> 'Adjust Lighting'). There is a slider whose default is 1.00. I think this like a "gamma". I typically increase this slightly (to around 1.05).

 

I think you can download a trial version of Photoshop Elements (from Adobe) that works for 30 days without a purchase (then buy a license key from somewhere later if you like it). It works on all file formats in 16 bits (and even 24-bit RAW) -- but it only handles layers in 8-bits (they want you to upgrade to the full Photoshop for 16-bit layers). So I only use the layers in that program after doing initial processing (in my case, I only use the layers for doing mosaics). I never found this "Lighten Shadows" function in other software (like GIMP -- which is better for deep sky).

 

Speaking of mosaics, I present one for the days Oct 6 (left) and 8 (right). The atmospheric conditions were very similar and so the quality was about the same on both days (slightly higher, I think on Oct 8). Click on the image below for higher resolution.

 

 

As it turns out, the apparent tilt of the Sun's axis is practically the maximum right now. I used the little program called "Tilting Sun" to verify this. I added a screenshot of the program to give some guidance for what is happening between the two images above (not as sophisticated as the Astro Bear Observatory).

 

Edited October 9, 2022 by thesmiths

[Jean-Francois P 217]

Hello Douglas,

 

With the nice full sun pictures ... you really need to participate to this collaboration with the Solar Orbiter team.

http://www.astrosurf.com/topic/157365-meesage-important-sur-la-campagne-proam-solar-orbiter/?tab=comments#comment-2221469

You can find a link to register and description of the project/collaboration in the message above.

 

Yes, I know the software Tilting Sun. It is fine ... I use it to verify my Python script for the calculation of the Carrington angle.

I will use it with my SharpCap script or with a modified version of your SHG script ... so that an automatic generation of the globe can be insert in the images.

 

Thanks for the description of your image processing with Photoshop Elements. (Arrr! ... not a new software).

I use for quick processing my PaintShopPro 7 and for longer process the PaintShopPro 2018. Both have one similar function.

I did now a quick test ... Hmm! it works too :-) ... I will use it in my future images.

It is much quicker as to select the disc, invert the selection and process the protuberances, then combine back with the disc.

Or maybe I can reprocess some of the old images ... I have now time during the long winter months ... until the sun will reappear next year :-)

 

Regards,

Jean-Francois

[thesmiths 285]

3 hours ago, Jean-Francois P said:

It is much quicker as to select the disc, invert the selection and process the protuberances, then combine back with the disc.

 

Yes, much faster and there is also not a discontinuity between two.

 

ImPPG, which I encouraged you to try, has a very interesting tone map also. But I prefer the "Lighten Shadows" function.

Edited October 9, 2022 by thesmiths

[maxip 326]

Le 09/10/2022 à 18:02, thesmiths a dit :

ImPPG, which I encouraged you to try,

Hello,

yes I definitely adopted ImPPG for deconvolution and tone mapping.

You can also try Photoshop > image > Ajustments > Shadows/Highlights.

Maxime