The weather remains sunny in London and now it's not so hot. The early morning gave some good seeing conditions. Another 330 GB of disk spaced used up by SHG video files, this time with H-alpha and H-beta (yesterday's H-alpha and Ca-H was about the same about of GBs). Two wavelengths is about what I can do while the Sun is in a favourable position.
The images are best seen at full resolution by opening in a new tab. You can toggle between the two images by switching between tabs. Use the little magnifier to click on an area to examine more closely (the size of the images are 3000 x 3000 pixels).
I also made some full size crops that fit on the screen better. The lower portion of images show some interesting structures that came out nicely inverted.
H-alpha and H-beta SHG full disk images from 7 Aug -- good seeing
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H-alpha and H-beta SHG full disk images from 7 Aug -- good seeing
Last edited by thesmiths on Tue Aug 09, 2022 8:48 pm, edited 1 time in total.
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Re: H-alpha and H-beta SHG full disk images from 7 Aug -- good seeing
I really enjoy your images Douglas!
I’m currently using the Sol’Ex but am limited by the slit to 480 mm focal length for a full disk. Is it possible to get a longer slit or would I need to modify the entire sgh?
I’m currently using the Sol’Ex but am limited by the slit to 480 mm focal length for a full disk. Is it possible to get a longer slit or would I need to modify the entire sgh?
James
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The Quark introduced me to this wonderful side of the hobby and the sun hasn’t disappointed yet.
Solar Equipment: Solar Spectrum RG-18 0.3A, Coronado Solarmax 90mm etalon Isle of Man SN-001, Tuscon SN-380 and Meade SM2, Lunt LS80 DS, Quark Chromosphere, Lunt 2" wedge, 2-Lunt CaK II 1200, Baader 3.8 and 5.0 solar film in 208mm cells, and 3D printed Sol'Ex SHG, Lunt 40mm
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These pretzels are making me thirsty! (C.C.)
The Quark introduced me to this wonderful side of the hobby and the sun hasn’t disappointed yet.
Solar Equipment: Solar Spectrum RG-18 0.3A, Coronado Solarmax 90mm etalon Isle of Man SN-001, Tuscon SN-380 and Meade SM2, Lunt LS80 DS, Quark Chromosphere, Lunt 2" wedge, 2-Lunt CaK II 1200, Baader 3.8 and 5.0 solar film in 208mm cells, and 3D printed Sol'Ex SHG, Lunt 40mm
Coming Soon: Solar Spectrum CaK II <1A filter
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Re: H-alpha and H-beta SHG full disk images from 7 Aug -- good seeing
The Solex design is fairly optimised so that all the lenses, slit, grating work together. You could probably figure out how to fit a longer slit onto the collimator, but the 25mm diameter optics means you probably don't have more than about 6mm which will be in good focus at the same time. So that means you can probably get to around 650mm focal length for a single scan.hopskipson wrote: ↑Sun Aug 07, 2022 6:22 pm I’m currently using the Sol’Ex but am limited by the slit to 480 mm focal length for a full disk. Is it possible to get a longer slit or would I need to modify the entire SHG?
I discovered also that with a long slit you need to have a way to adjust for tilt of the slit and I think also for tilts of the other optical elements.
Finally, take into account the magnification of the system. With the 80/125 standard Solex design, the image size at the sensor will be 9.4mm for a 650mm focal length. So you might need a larger camera sensor. Alternatively, consider replacing the 80mm focal length lens with another 125mm lens to reduce the magnification to 1. But then the collimator needs to be redesigned for the longer focal length.
So as you can see, you start to open up a can of worms when you think about doing a longer focal length in a single scan. The other way is to just do 2 scans and mosaic them together.
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Re: H-alpha and H-beta SHG full disk images from 7 Aug -- good seeing
I just noticed this nice image by my friend Jean Francois (JFP), who also uses the standard Solex. He made the following nice image using a 102mm focal length telescope, just with 3 passes and then did a mosaic http://www.astrosurf.com/uploads/monthl ... 262d0b.jpghopskipson wrote: ↑Sun Aug 07, 2022 6:22 pm I’m currently using the Sol’Ex but am limited by the slit to 480 mm focal length for a full disk.
He is the one who introduced me to the idea of stacking SHG images. He's quite good at building things but he admitted that attempting to put a long slit into a Solex would be a total rebuild, so he is sticking to making mosaics for now. Here is the link to his full post on astrosurf: http://www.astrosurf.com/topic/156088-s ... ohp-solex/
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Re: H-alpha and H-beta SHG full disk images from 7 Aug -- good seeing
Fantastic images Douglas
Do you know what height in the chromosphere hydrogen beta is looking at?
Alexandra
Do you know what height in the chromosphere hydrogen beta is looking at?
Alexandra
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Re: H-alpha and H-beta SHG full disk images from 7 Aug -- good seeing
That's a really interesting question. I had a look around and the best I could find was the following statement regarding H-beta: "the features originate from a height region in the solar atmosphere that spans the photosphere (the ‘surface’ of the sun) and the chromosphere". https://nso.edu/press-release/first-hig ... lar-image/
Compare to this statement: "The hydrogen-alpha and calcium-K bands are those that show the most excitingly distinct features compared to broadband observing. Hydrogen-alpha light shows the middle to upper chromospheric features, including filaments on the disc and the highly dynamic prominences visible at the limb. It also gives a different perspective on sunspots and reveals the magnetic active areas that do not show spots. Calcium-K light reveals a lower, cooler layer of the chromosphere, showing the bright chromospheric network, plage, and the magnetic regions strongly." https://britastro.org/journal_contents_ ... narrowband
I also found this interesting webpage, which does not really answer your question but has an interesting story to tell: https://www.icstars.com/apage1/2011/2011_Sept01.html
Last edited by thesmiths on Wed Aug 10, 2022 10:48 am, edited 1 time in total.
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Re: H-alpha and H-beta SHG full disk images from 7 Aug -- good seeing
Very interesting!! the third link shows that h-beta is very similar to the wings of h-alpha (the offband image in h-alpha that they show). So I reckon it's height is between halpha and photosphere.
Alexandra
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Re: H-alpha and H-beta SHG full disk images from 7 Aug -- good seeing
Yup, sounds right to me.
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