The unusual spectrum of comet 96P/Machholz

We report spectra from 3000 to 5900 angstrom for comet 96P/Machholz, obtained on 2007 April 27 UT with the 3 m Shane telescope at Lick Observatory. The spectra are extremely carbon-poor, and they show a prominent NH2 series but no CN emission. NH, NH2, and C-2 gas production rates are (8.36 +/- 2.18) x 10(25), (29.88 +/- 3.66) x 10(25), and (4.52 +/- 0.61) x 10(23) molecules s(-1), respectively, as determined from Haser model fits to the data. Upper limits to the gas production rates for CN and C-3 are 7.5 x 10(22) and 2.0 x 10(23), respectively. Although 96P is depleted in C-2 and C-3 relative to NH, it is even more depleted in CN than other so-called carbon chain-depleted comets.