London has had a streak of nice days of weather so I've taken the opportunity to keep practicing with our updated SHG. Today's seeing was better than yesterday and the SHG images were noticeably sharper. For the Calcium imaging, I chose the Ca-H line (it is a little narrower than Ca-K, which makes it easier to acquire data) and I used a 72mm aperture mask, bringing the focal ratio down to f10. The results are probably our best so far -- focus is now very good across almost the full disk at 720mm focal length. The quality now depends mainly on the atmospheric conditions.
Comparing to images on the same day from Rainer, the quality of full-disk SHG images in H-alpha are now similar to good etalon images https://rainerehlert.com/00_SCHForum/20 ... _9Q_RE.jpg (I'm not sure if Rainer's images are single or double stacked and what aperture he used -- maybe someone can let me know). Full-disk Calcium SHG images are now likely better, or at least more revealing, than Calcium filter images.
All images look best when opened in a new tab.
I think the inverted H-alpha image above looks interesting next to the Ca-H image below:
Here is a closeup of one of the fairly active regions in H-alpha, taken from a different set of scans than the full disk image above. It looked quite nice inverted.
And, finally, here is the same region in Ca-H, taken from the full disk image above.
H-alpha and Ca-H full disk images from 6 Aug -- very good resolution
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H-alpha and Ca-H full disk images from 6 Aug -- very good resolution
Last edited by thesmiths on Tue Aug 09, 2022 8:56 pm, edited 1 time in total.
- marktownley
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Re: H-alpha and Ca-H full disk images from 6 Aug -- very good resolution
Stunning results Douglas!
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Solar images, a collection of all the most up to date live solar data on the web, imaging & processing tutorials - please take a look!
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Re: H-alpha and Ca-H full disk images from 6 Aug -- very good resolution
Your discs are absolutely breath taking, your CaH makes my heart sing
I think Rainer uses a DS Coronado 60mm
Alexandra
I think Rainer uses a DS Coronado 60mm
Alexandra