3 Scientific objectives

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The observation of the GRB error box simultaneously to the GRB occurrence ($\sim$ 6 GRBs per year). The faint transient emission that has been detected few hours after the event, seems to be a consequence of the expanding remnant produced by the GRB. This provides information about the surrounding medium, but not about the burster itself. Although these optical counterparts are not brighter than 19 mag a few hours after the burst, transient emission simultaneous to the event is expected to be more intense. In fact, an extrapolation of the $\gamma$-ray power-law spectrum indicates that the simultaneous optical flash should lie in the range 10-15 mag, depending on the burst intensity. Current theories predict that there should be an optical flash reaching a red broad-band magnitude R $\sim$ 10 or brighter, as has been seen for the first time in GRB 990123 (Akerlof et al. 1999).

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The detection of optical flashes of cosmic origin, that could be unrelated to GRBs and would be a different astrophysical phenomenon (perhaps associated to QSOs/AGNs). In fact some GRB models predict that there should be a large number of bursting sources in which only transient X-ray/optical emission should be observed, but no $\gamma$-ray emission. The latter would be confined in a jet-like structure and pointing towards us only in a few cases.

  

Table 3: Quick follow-up GRB observations during 1998

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The observation of the sky in the ${\vec I}$ and ${\vec V}$ filters, as a part of the preparations for the ESA's satellite project INTEGRAL (the International Gamma-Ray Laboratory), in which Spain and the Czech Republic are involved with the Optical Monitoring Camera (OMC, Más-Hesse et al. 1998). The preparation includes test of technologies, data processing, ground based observational network, etc.

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The monitoring of several objects (bright AGNs/QSOs, old GRB positions, etc.) looking for recurrent transient optical emission arising from these sources (Hudec et al. 1996). There are hints that sudden and rapid flares occur. This will be achieved by means of the 0.3-m BOOTES telescope.