  We present the gravitational wave analysis from rotating (model s15g) and
nearly non-rotating (model s15h) 3D MHD core collapse supernova simulations at
bounce and the first couple of ten milliseconds afterwards. The simulations are
launched from 15M_{\odot} progenitor models stemming from stellar evolution
calculations. Gravity is implemented by a spherically symmetric effective
general relativistic potential. The input physics uses the Lattimer-Swesty
equation of state for hot, dense matter and a neutrino parametrisation scheme
that is accurate until the first few ms after bounce. The 3D simulations allow
us to study features already known from 2D simulations as well as
nonaxisymmetric effects. In agreement with recent results we find only type I
gravitational wave signals at core bounce. In the later stage of the
simulations, one of our models (s15g) shows nonaxisymmetric gravitational wave
emission caused by a low T/|W| dynamical instability, while the other model
radiates gravitational waves due to a convective instability in the
protoneutron star. The total energy released in gravitational waves within the
considered time intervals is 1.52\times10^{-7}M_{\odot} (s15g) and
4.72\times10^{-10}M_{\odot} (s15h). Both core collapse simulations indicate
that corresponding events in our Galaxy would be detectable either by the LIGO
or Advanced LIGO detector.
