  The NaI and BGO detectors on the Gamma ray Burst Monitor (GBM) on Fermi are
now being used for long term monitoring of the hard X-ray/low energy gamma ray
sky. Using the Earth occultation technique demonstrated previously by the BATSE
instrument on the Compton Gamma Ray Observatory, GBM produces multiband light
curves and spectra for known sources and transient outbursts in the 8 keV - 1
MeV band with its NaI detectors and up to 40 MeV with its BGO. Coverage of the
entire sky is obtained every two orbits, with sensitivity exceeding that of
BATSE at energies below ~25 keV and above ~1.5 MeV. We describe the technique
and present preliminary results after the first ~17 months of observations at
energies above 100 keV. Seven sources are detected: the Crab, Cyg X-1, Swift
J1753.5-0127, 1E 1740-29, Cen A, GRS 1915+105, and the transient source XTE
J1752-223.
