Wide Field Cameras of BeppoSAX have played the key role in these new developments. Their imaging capability, with a pixel size of 5 minute of arc, and even smaller error boxes for good statistics, has been the key improvement in this new astrophysics, when included in the frame of a more general detection strategy. In particular difficulties arise from the absence of any onboard trigger for the WFC and from the absence of a robust and fast detector of new sources. This is a consequence of the coded mask technique applied to a large field including several sources, and of the general architecture of the BeppoSAX data handling system, the onboard recording and the downloading once per orbit. The potentiality of the WFC is fully exploited when the Gamma-Ray Burst Monitor provides an onboard generated trigger that steers the search for transient events in the WFC light curve and reduces the search for a GRB to a very small fraction of the total time. Moreover the Narrow Field Instruments of SAX, under the control of the same team, can be pointed to the WFC position as soon as it is derived from the image. During 1996 a series of operations included commissioning, science verification and various adjustment of thresholds and trigger conditions made the number of GRBM triggers reasonable. During this transition a first GRB (960720 Piro et al. 1998a) was detected with WFC and, starting from this point, a procedure was developed that became fully operative at the beginning of December 1996 (described in Costa et al. 1998).
The whole BeppoSAX payload was in stand-by for around two months in summer 1997 because of the premature deterioration of some gyroscopes. With the present pointing system, that makes use of a single gyroscope, the follow up pointing of narrow field instruments may be slower and the burst positioning capability in certain conditions is worse than it was before, but these delays have been off-set by improved procedures, software and skill in various areas.
A gyro-less pointing mode is about to be tested and will be adopted as soon as the last gyroscope becomes obsolete. A further, but not dramatic, slowing of pointing rapidity is expected from this new mode. The BeppoSAX mission, and the associated GRB program, is expected to last at least two more years.
In Table 1, we show the Gamma-Ray Bursts detected with WFCs and GRBM until November 1998, with peak fluxes and duration in the band of the two instruments. All the bursts in the list belong to the class of long burst.
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