is the hydrogen beta line in the solar spectrum.
I derived the background from an image taken through a homebuilt spectroscope at Ryerson Observatory.
Here's a couple of crops of the same image:
And another one: Blue solar spectrum
I have a link to a PDF of an analysis of the absorption lines here:
The sharp line just to the left of H-beta is Fe I, or unionized iron, for instance. I resized the image to match the scale on the PDF (at least how it appears on my computer); putting the two together gets you identifications of the lines in my image.
It isn't perfect--on the spectrum I did a motion blur in the vertical direction to smooth out noise, but I know everything is not perfectly vertical (I think there is some curvature of field in the spectroscope, and probably in the camera lens). In addition, the hydrogen beta line is definitely not symmetrical.
It's kinda neat that you can say there's iron, nickel, chromium, cobalt, titanium, and even maybe vanadium in the sun, yes?
I'm not sure I'm keeping this design, but for the moment it stays.