Thanks Ken,
That pretty much is what I thought (though perhaps not in those terms), essentially we are looking at the HA band within the context of the the overall light spectrum; ie: blue to red, and then taking that into the subset of the HA bandwidth that we are viewing.
So, in terms of HA tuning via the etalon..., specifically in my case a pressure tuned unit, am I correct in assuming that with my tuner wound out (lower air pressure), I achieve longer wavelengths, relatively speaking & am thus at the blue wing whereas when wound in (higher air pressure) I achieve shorter wavelengths & am thus at the red wing? Somewhere in the central point of my pressure tuner will be the mid point of the HA band that I am observing.. does that sound correct in basic terms or, am I completely off track?
I am hopeful that by understanding how this tuning works, relative to the spectrum & combined with the information you provide in your posts, I can better understand the tuning of my scope & begin to better understand what features will show best at which tuning points & with time & experience, everything in between.
Cheers
Carlton
Quote:
Originally Posted by Merlin66
Carlton,
The H alpha solar absorption line when you look at the profile, is like a deep valley with wider top section. The width of the line is >2A. Beyond the wider section we move from H alpha into the solar continuum.
Simplistically, if our H alpha filter has a bandwidth of <1A then we can position it at the deepest (central section) or out in the wider sections....
The wider top sections are the "wings" of the Ha line - the blue wing towards the blue, and red the opposite.
When we observe at the Ha core (6262.8 A CWL (central wavelength)) we are looking at a region of the Chromosphere around 1500 Km above the "White light" Photosphere. As we move our filter (tuning) out into the "wings" we start to see detail lower in the Chromosphere - 200 - 300 Km above the Photosphere.
Besides the possible Doppler shift (which changes the appearance of some of the filaments - which also requires working in the wings), the wings also allow us to better see and record things like Ellerman Bombs and flares.
Hope this helps.
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