Abstract
We describe the space project of Ultra-Fast Flash Observatory (UFFO) which will observe early optical photons from
gamma-ray bursts (GRBs) with a sub-second optical response, for the first time. The UFFO will probe the early optical
rise of GRBs, opening a completely new frontier in GRB and transient studies, using a fast response Slewing Mirror
Telescope (SMT) that redirects optical path to telescope instead of slewing of telescopes or spacecraft. In our small
UFFO-Pathfinder experiment, scheduled to launch aboard the Lomonosov satellite in 2012, we use a motorized mirror in
our Slewing Mirror Telescope instrument to achieve less than one second optical response after X-ray trigger. We
describe the science and the mission of the UFFO project, including a next version called UFFO-100. With our program
of ultra-fast optical response GRB observatories, we aim to gain a deeper understanding of GRB mechanisms, and
potentially open up the z<10 universe to study via GRB as point source emission probes.
