  Since the discovery of Gamma-Ray Bursts (GRBs), attempts have been made to
detect correlated optical transient emission from these objects. In January
1999, the ROTSE I robotic telescope detected a bright optical flash
simultaneous with a GRB, thanks to the prompt dissemination to the ground of
the high energy event coordinates. To date, that single observation remains
unique as no other prompt flashes have been seen for other bursts observed with
comparably short response times. This suggests that in general GRB prompt
optical emission may be considerably dimmer than observed for the GRB990123
event. To exploit the better angular localization accuracy of the flying
(HETE-2) or soon to fly (INTEGRAL, AGILE, SWIFT, GLAST) missions for high
energy astrophysics, a new generation of robotic telescopes is being developed.
These will have response times as short as a few seconds and will be sensitive
to signals as faint as m_v ~ 20, thus increasing the chance of detecting even
weak prompt emission. Results from these experiments should provide important
new data about the dynamics and local medium composition of GRBs. In this paper
we describe one of the new instruments, ROSS, to be mounted on the robotic
facility REM, designed to perform low resolution spectroscopy on the prompt
optical flares associated with GRBs.
