We describe a spectroscopic survey designed to uncover an estimated \sim 40 AM CVn stars hiding in the photometric database of the Sloan Digital Sky Survey ( SDSS ) .
We have constructed a relatively small sample of about 1,500 candidates based on a colour selection , which should contain the majority of all AM CVn binaries while remaining small enough that spectroscopic identification of the full sample is feasible .

We present the first new AM CVn star discovered using this strategy , SDSS J080449.49+161624.8 , the ultracompact binary nature of which is demonstrated using high-time-resolution spectroscopy obtained at the Magellan telescopes at Las Campanas Observatory , Chile .
A kinematic ‘ S-wave ’ feature is observed on a period P _ { \mathrm { orb } } = 44.5 \pm 0.1 min , which we propose is the orbital period , although the present data can not yet exclude its nearest daily aliases .

The new AM CVn star shows a peculiar spectrum of broad , single-peaked helium emission lines with unusually strong series of ionised helium , reminiscent of the ( intermediate ) polars among the hydrogen-rich Cataclysmic Variables .
We speculate that SDSS J0804+1616 may be the first magnetic AM CVn star .
The accreted material appears to be enriched in nitrogen , to N/O \gtrsim 10 and N/C > 10 by number , indicating CNO-cycle hydrogen burning , but no helium burning , in the prior evolution of the donor star .