text: 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. 