What a quiet sun today! Disc & Surface in CaK, Aug 31 2018

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What a quiet sun today! Disc & Surface in CaK, Aug 31 2018

Post by MalVeauX » Fri Aug 31, 2018 5:37 pm

Heya,

Man, what a quiet sun today. Very few prom groups that are impressive. Very few faculae. No spots at all. Really, truly, a nearly void disc. At high resolution you can see some minor active areas that are interesting, but they're very tiny, and scattered. There's an active area coming around the limb that is slightly interesting, but no proms near it, and all the big filaments are pretty much gone too. So I just chose some random areas with some activity and only imaged in 3934A today and took a look at the small active area coming around the limb and the larger active field near the center of the disc.

100mm (masked the 6") F12 refractor with Chroma 393.4 BP1nm & PST CaK Filter with ASI174MM & 3x Barlow for the larger scale images.
40mm F10 refractor without the barlow for the small scale image of the disc.

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Colored versions:

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setup_08312018.jpg
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Conditions (eye roll!)
conditions_08312018.jpg
conditions_08312018.jpg (74.01 KiB) Viewed 418 times
Very best,

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Re: What a quiet sun today! Disc & Surface in CaK, Aug 31 2018

Post by krakatoa1883 » Fri Aug 31, 2018 7:33 pm

Very good images, Marty, stopping down the aperture makes contrast higher. With my 150 f/5 I can't go beyond 100mm, the same aperture with your f/8 ensures better definition and sharpness.

May I suggest not to burn the center of the disc but try to obtain a more uniform brightness between center and edge, something like this
marty fd mod.jpg
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Re: What a quiet sun today! Disc & Surface in CaK, Aug 31 2018

Post by MalVeauX » Fri Aug 31, 2018 7:50 pm

Thanks Raf,

Mind sharing how you adjusted the curve for the more uniform look?

Thanks!

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Re: What a quiet sun today! Disc & Surface in CaK, Aug 31 2018

Post by krakatoa1883 » Fri Aug 31, 2018 7:51 pm

I lowered the right side of the "curves" function in GIMP

https://docs.gimp.org/en/gimp-tool-curves.html
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Re: What a quiet sun today! Disc & Surface in CaK, Aug 31 2018

Post by Carbon60 » Fri Aug 31, 2018 8:09 pm

Very nice CaK images, Marty, even for a quiet sun.

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Re: What a quiet sun today! Disc & Surface in CaK, Aug 31 2018

Post by MalVeauX » Fri Aug 31, 2018 8:13 pm

krakatoa1883 wrote:
Fri Aug 31, 2018 7:51 pm
I lowered the right side of the "curves" function in GIMP

https://docs.gimp.org/en/gimp-tool-curves.html
Thanks,

I tried lowering the right of the curve to match the angle of the histogram. What do you think?
Disc-Edit.jpg
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Re: What a quiet sun today! Disc & Surface in CaK, Aug 31 2018

Post by krakatoa1883 » Fri Aug 31, 2018 8:32 pm

Much better, very nice!
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Re: What a quiet sun today! Disc & Surface in CaK, Aug 31 2018

Post by MalVeauX » Fri Aug 31, 2018 8:33 pm

Thanks all,

Always appreciate input to improve. :bow

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Re: What a quiet sun today! Disc & Surface in CaK, Aug 31 2018

Post by Montana » Mon Sep 03, 2018 9:07 am

Stunning hi res, I think that is going to be what will be of most interest over minimum :hamster: :bow

Can I ask what is wrong with the first full disc? when I look through the telescope the Sun does look like that, so why does it have to be flat? see the blue image (CaK) here too https://www.kso.ac.at/index.php

Alexandra

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Re: What a quiet sun today! Disc & Surface in CaK, Aug 31 2018

Post by MalVeauX » Mon Sep 03, 2018 9:24 am

I think it's just another paradigm of presentation. :)

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Re: What a quiet sun today! Disc & Surface in CaK, Aug 31 2018

Post by Valery » Wed Sep 05, 2018 1:19 am

PST filter makes a great difference in your images! Nice shots.
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Re: What a quiet sun today! Disc & Surface in CaK, Aug 31 2018

Post by krakatoa1883 » Thu Sep 06, 2018 10:13 am

Montana wrote:
Mon Sep 03, 2018 9:07 am
Can I ask what is wrong with the first full disc? when I look through the telescope the Sun does look like that, so why does it have to be flat? see the blue image (CaK) here too https://www.kso.ac.at/index.php
Hi Alexandra, today I spent few minutes looking through my calcium Quark (in spite of Daystar's claims on its safety I wouldn't recommend this exercise to anyone) and I noted that yes there is some center brightening and limb darkening but they are subtle, less evident than in WL. However I think that flattening the disc it's a matter of personal taste at least for our purposes here.
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Re: What a quiet sun today! Disc & Surface in CaK, Aug 31 2018

Post by marktownley » Sat Sep 08, 2018 11:37 am

Great set of images Marty! That's a great homebrew CaK filter you have there.
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