It was sunny today but it turned out there was far too much air turbulence to do nice SHG imaging. Nevertheless, I was able to start with CaH and then change the grating angle and refocus the optics to capture a few H-alpha images. It's not often that I've been able to capture both wavelengths in the same imaging session. The setup was the same as before viewtopic.php?f=8&t=34047.
The H-alpha data was taken with an exposure of 4ms, gain of 95, scanning speed of 10x (this should have been higher; the Y/X ratio was 1.36). The CaH data was taken with an exposure of 10ms, gain of 157 and scanning speed of 8x. There are small regions of good resolution when the air was stable. But since it takes around 15s to complete a scan, the few seconds of stability was not enough to cover a full image.
It's interesting to see that the H-alpha and CaH prominences look completely different in structure. I had not noticed before how different they could be.
H-alpha and CaH SHG comparison
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Re: H-alpha and CaH SHG comparison
Terrific comparisons Doug every week you show something new and interesting I'm guessing the CaK emission and Halpha emission are in different areas of the prominence. I think Stephen from his studies found that only the most energic proms seem to emit in the CaK, maybe these are the most active parts and the tree trunks so visible in Halpha are actually quite stable? no idea really, just guessing.
Alexandra
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Re: H-alpha and CaH SHG comparison
Hi Alexandra: yes, I think the H-alpha to Calcium prom comparison is worth more study. I think the Calcium proms are much easier to capture with the SHG due to the narrow bandwidth. The Hydrogen proms are easier with a normal filter. I'll try that comparison next time. I have a slightly improved Calcium setup I'm hoping to test, weather permitting.I think Stephen from his studies found that only the most energic proms seem to emit in the CaK
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Re: H-alpha and CaH SHG comparison
Very impressive results Douglas!
http://brierleyhillsolar.blogspot.co.uk/
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