[Rob_K]

Thanks to heavy rain clearing out the NE skies I've been able to take spectra of two comets over the last two nights. I completed my spectrum hunt tonight by taking one of C/2011 L4 (PANSTARRS). Because of pretty basic gear I needed two bright comets, and what better than Lemmon & PANSTARRS, one gassy and one dusty!

These are low resolution spectra taken without a slit and the DSLR camera response limits the wavelength range, but nonetheless the differences are pretty dramatic IMO. Broadly, Lemmon appears to shine strongly in the emitted light of diatomic carbon, while PANSTARRS shines in the reflected light of the Sun with only one strong emission line, sodium at 589nm. It does also have some very weak emission lines in diatomic carbon. Unfortunately my camera won't pick up the strong CN spike that Lemmon has because it is too far into the ultraviolet.

I was unable to replicate the last Lemmon spectrum I posted in Terry's thread because that camera died, RIP. I've had to do some re-calibration of my images, trust that this is around the mark.

Cheers -