  We report the discovery of a new slowly pulsating B (SPB) star, with the
largest number of detected frequencies to date by more than a factor of three,
based on 37 days of MOST (Microvariability & Oscillations of STars) satellite
guide star photometry. The star HD 163830 (V = 9.3, B5II/III) varies in twenty
detected frequencies in the range $0.035 - 1.06$ d$^{-1}$ ($0.4 - 12.3 ~
\mu$Hz) with amplitudes from 0.7 to 7.6 mmag ($S/N$ from {4 to 43}). Eighteen
of these frequencies are consistent with low-degree, high-order nonradial
g-modes {of seismic models of an evolved 4.5$M_{\odot}$ star. We are unable to
identify one unique model due to lack of mode identifications. The lowest two
frequencies may be associated with the rotation of HD 163830, but firm proof of
this must await future spectroscopic data.
