  We present an analysis of more than 11 years of Fermi-GBM data in which 217
Gamma-Ray Bursts (GRBs) are found for which their main burst is preceded by a
precursor flash. We find that short GRBs ($<$2 s) are ~10 times less likely to
produce a precursor than long GRBs. The quiescent time profile is well
described by a double Gaussian distribution, indicating that the observed
precursors have two distinct physical progenitors. The light curves of the
identified precursor GRBs are publicly available in an online catalog
(https://icecube.wisc.edu/~grbweb_public/Precursors.html).
