  Wayne is an algorithm that simulates Hubble Space Telescope (HST) Wide Field
Camera 3 (WFC3) grism spectroscopic frames including sources of noise and
systematics. It can simulate both staring and spatial scan modes, and
observations such as the transit and the eclipse of an exoplanet. Unlike many
other instrument simulators, the focus of Wayne is on creating frames with
realistic systematics in order to test the effectiveness of different data
analysis methods in a variety of different scenarios. This approach is critical
for method validation and optimising observing strategies. In this paper we
describe the implementation of Wayne for WFC3 in the near-infrared channel with
the G102 and G141 grisms. We compare the simulations to real data, obtained for
the exoplanet HD 209458 b to verify the accuracy of the simulation. The
software is now available as open source at
https://github.com/ucl-exoplanets/wayne.
