Filament structure and protuberances in CaH with SHG

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thesmiths
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Filament structure and protuberances in CaH with SHG

Post by thesmiths »

Using the same setup as for H-alpha two days before, I attempted to see filament structure at the CaH wavelength (see viewtopic.php?f=8&t=34047). The filaments have faded a bit in the meantime but they are visible in CaH (although they are not as noticeable as I had hoped).

CaH with SHG at 700mm -- surface structure
CaH with SHG at 700mm -- surface structure
130147_clahe.jpg (44.97 KiB) Viewed 103 times
CaH SHG -- protuberances
CaH SHG -- protuberances
130147_protus.jpg (16.81 KiB) Viewed 103 times
This data was taken on 25 November at 13:01. It can be compared to the H-alpha and CaK images taken on the same day with filters: viewtopic.php?f=4&t=34061

The atmospheric conditions were only fair and the imaging was again done through the bedroom window. But clearly the filament structure and the protuberances are more apparent than with a typical CaK filter. However, with SHG you really need exceptionally good seeing conditions because of the long time scales involved (this single image took 30 seconds to acquire). The shutter speed was 8ms and the gain was 224 (43%).


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Re: Filament structure and protuberances in CaH with SHG

Post by thesmiths »

Here is a mosaic of pixel shifted images that goes from -32 to 28 pixels in steps of 4. Only the images at or very near to zero (the centre of the CaH spectral line) show the filament structures. The mosaic is actually quite large so best to click on it to view at higher resolution.

CaH pixel shifted mosaic
CaH pixel shifted mosaic
130147 shift -32 to 28.jpg (309.61 KiB) Viewed 97 times

The images are not symmetrical around zero since the CaH spectral line is not symmetrical, as can be seen in this actual video frame.

single frame of the CaH spectral line
single frame of the CaH spectral line
frame-2198.jpg (17.1 KiB) Viewed 97 times

The size of the video ROI is 2000x200 so -32 to +28 (a width of 60 total pixels) corresponds to 30% of the height of the image, or more or less the width of the dark region visible in this frame.


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Re: Filament structure and protuberances in CaH with SHG

Post by marktownley »

Excellent results Douglas, seeing the results from the SHGs in CaK is giving me plenty of food for thought of how I can develop the use of my own CaK system next year. The mosaic is excellent showing either side of centre line, very informative.


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Re: Filament structure and protuberances in CaH with SHG

Post by Montana »

Terrific information and images (excellent proms) :bow :hamster: the series of images are really useful for gauging our Lunt modules and CaK PSTs :bow

Alexandra


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Re: Filament structure and protuberances in CaH with SHG

Post by Montana »

Interesting that the proms seem to be visible in at centre line images and off to the right, but not in those to the left. Some folks with a Lunt modules can see proms, others cannot. I guess my Lunt module is on the unlucky left of CL and those who can see proms are on the lucky right of CL.

Alexandra


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Re: Filament structure and protuberances in CaH with SHG

Post by thesmiths »

Hi Alexandra: I made a new mosaic to investigate your observations about the prominences. The top row below is 0 to +4 and the bottom row is 0 to -4 (from left to right in both cases). It is a large image (5000x1000 pixels!) so you need to click on it to see the fine details. To see at maximum resolution, you can look at the image cache itself download/file.php?id=61568 in a new tab and then click on the image again to see the full resolution.

CaH prominences -- 0 to 4 and 0 to -4
CaH prominences -- 0 to 4 and 0 to -4
130147_protus_-4_to_4.jpg (362.23 KiB) Viewed 77 times

My impressions: the centre of the spectral line shows the prominences the best and visibility falls off pretty quickly; shifting minus and positive shows different structures but it might just be a Doppler effect rather than a consistent bias to one side or the other.

I believe that a positive shift corresponds to an upward shift in the spectrum, which would mean more towards the blue (but I should try to check that that assumption is correct).

My guess for why prominences appear in some Lunt filters is more just being closer to the centre of the CaK line. The wider bandwidth of the filter I think is kind of like taking an average over a range of the pixel shifted SHG images.


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Re: Filament structure and protuberances in CaH with SHG

Post by Merlin66 »

Not my graph, but a good representation of the problem imaging detail within the CaK bandwidth.
2A is too wide to pick up and isolate the finer K2 detail.
IMG_0245.JPG
IMG_0245.JPG (126.2 KiB) Viewed 62 times
Doug,
I believe that a positive shift corresponds to an upward shift in the spectrum, which would mean more towards the blue (but I should try to check that that assumption is correct) - A positive shift is towards the red wing.....


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Re: Filament structure and protuberances in CaH with SHG

Post by marktownley »

Great info guys!


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