1 Introduction

The detection of the faint optical afterglows in the last two years has not solved the mystery of GRBs. The optical behaviour of GRBs in the very early onset of the $\gamma$-ray emission and earlier is unknown because no simultaneous observations have been obtained up to now over 10 mag (Bernas et al. 1998). Even the recently discovered optical emission from GRB 990123 at the level of 9-12 mag was detected by ROTSE only 22.18 s after the onset of the burst (Akerlof et al. 1999).

The hope of finding some signature of the nature of the GRB parent bodies probably rests with the observation of OTs, possibly simultaneously with $\gamma$-ray emission. The difficult observations of light flashes, unpredictable in time and position, started on the basis of the archival astroplates analysis (Greiner & Wenzel 1990, and references therein).

Since the typical duration of a GRB is as short as a few seconds, with a very fast rising time and a temporal evolution characterized by a strong stochastic variability, an "ad hoc" projected telescope should have high time resolution, good sensitivity and obviously a very wide field of view. The request of spatial resolution is less important because a precise localization can be devolved to the observations of the afterglow. Practically no OT monitoring project combining these conditions exists.

For these reasons we propose the project of an optical telescope scanning the field of view of a $\gamma$-telescope during its observation and accumulating information about faint OTs independently from GRBs detection (and data about precise GRBs position).