GCN Circular 2817
J. Wren, W.T. Vestrand, P. Wozniak, R. White, report on behalf of the RAPTOR team. Stereoscopic observations collected by the RAPTOR wide-field sky monitoring systems allow us to place optical limits on a prompt optical flash from GRB 041016 (HETE trigger 3578). The earliest images were 10 second exposures obtained starting at 04:40:13.3 UT (35 seconds after the GRB trigger) with a limiting magnitude of R ~ 13.1 mag. When compared to our later follow-up images and sky patrol images taken earlier in the evening, no new or variable objects were detected (other than known asteroids). Straightforward extrapolation of the light curve for prompt optical emission measured from GRB 021211, an event with approximately half the 25-300 keV fluence of GRB 041016, predicts an optical flux that exceeds these early flux limits.