Search for prompt optical emission from gamma-ray bursts

The ROTSE project (Robotical Optical Transient Search Experiment) has developed two sets of instruments for detecting optical transients. The first, ROTSE-I, is a four-fold array of telephoto lenses with CCD cameras on a single rapid slewing mount. Fully operational since April 1998, it records images following a BATSE trigger with a typical delay of 10 seconds from the initial satellite detection. The average rate of such events is one per week and the limiting magnitude is in the range of 14 to 16, depending on total integration time. The second set of instruments, ROTSE-II, is a pair of 0.45 m aperture telescopes capable of reaching a threshold, m_v<20. The first member of this pair should be operational by September 1998. We will report on the data obtained with both sets of instruments up until December 1998.