Fermi GBM observations of the hard x-ray spectrum of Mrk 421

The Gamma-ray Burst Monitor (GBM) on Fermi uses the Earth Occultation technique for long-term monitoring of the hard X-ray/low energy gamma-ray sky. GBM produces multi-band light curves and spectra for known sources and transient outbursts in the 8 keV to 1 MeV energy range with its NaI detectors and up to 40 MeV with its BGO detectors. Mrk 421, one of the brightest and closest (z=0.031) established TeV blazars, is listed as a marginal detection in the GBM 3 year catalog. In this work, we report on five years of monitoring results for Mrk 421. Mrk421 was active between 2009 and 2010. The spectrum from the joint MAXI and GBM data in the range of 2-60 keV show clearly a curved spectrum fitted by a Log Polynomial function.