  We present the S-PLUS Transient Extension Program (STEP): a supernova and
fast transient survey conducted in the southern hemisphere using data from the
Southern Photometric Local Universe Survey (S-PLUS) Main Survey and the
T80-South telescope. Transient astrophysical phenomena have a range of interest
that goes through different fields of astrophysics and cosmology. With the
detection of an electromagnetic counterpart to the gravitational wave (GW)
event GW170817 from a binary neutron stars merger, new techniques and resources
to study fast astrophysical transients in the multi-messenger context have
increased. In this paper, we present the STEP overview, the SN follow-up data
obtained, data reduction, analysis of new transients and deep learning
algorithms to optimize transient candidate selection. Additionally, we present
prospects and optimized strategy for the search of Gravitational Wave
counterparts in the current LIGO/Virgo/Kagra observational run (O4) in the
context of T80-South telescope.
