  The secondary instrument onboard Fermi, the Gamma-ray Burst Monitor (GBM) is
an all sky monitor consisting of 14 scintillation detectors. When analysing
transient events such as Gamma-Ray Bursts (GRBs) and Solar Flares (SFs) the
background is usually modelled as a polynomial (order 0-4). However, for long
events the background may vary more than can be accounted for with a simple
polynomial. In these cases a more accurate knowledge of GBM's background rates
is required. Here we present an alternative method of both determining the
background and distinguishing low-level emission from the instrumental
background.
