I had another play tonight (it's glorious outside!). For a challenge I thought I'd try collecting spectra of the Galilean moons. I had some mixed success.
Io and Europa were very close together at the time and the glare from Jupiter ruined that spectra anyway. The Callisto spectrum didn't show much in the way of structure at all, but I got a definite line at approx. 6888A in the Ganymede spectrum.
My processing was as follows:
I captured a Gamma Crucis spectrum first for reference and calibration.
The Ganymede spectrum was normalised, corrected for instrument response, and then I divided the corrected spectrum by the G2V library spectrum. There's a bit of noise in the spectrum but the line at 6888A is definite. I'm guessing it would be a molecular band rather than an element. Any clues?
Al.