Jeremy, Andy, Robin, Thanks for your comments. I will go ahead and revive my setup but I’m not the best of experimentalists so if anybody could provide me with a high res Hbeta spectrum (raw fits file + calibration fits file) it would be a good check on my abilities! As I said in my original post, I have some data supplied to me (scattered daylight) which is practically identical to my data at Halpha but there is a discrepency at Hbeta (min intensity ~ 0.2 compared to my value of ~ 0.35) which I would like to resolve. In my analysis method I need an accurate zero which I obtain by subtracting, from my raw europa spectrum, a neighbouring strip off the fits file. I’ve no idea how a zero level is determined in the scattered daylight method, is the intensity so great that it just overwhelms any zero error?
My ultimate aim is to test my expression for thermal equilibrium photon capture cross-sections (equation 6.32 in my theory document on my website http://www.thewhightstuff.co.uk) which applies generally to any element (hence the interest in Na D lines). I still do not know if this a previously known equation or even correct.
Regards
Ken
British Astronomical Association
Supporting amateur astronomers since 1890