Here's another. Can we beat this?
http://lheawww.gsfc.nasa.gov/docs/gamco ... /2822.gcn3
"The BOOTES-2 very wide field camera located at the Estación
Experimental de La Mayora (EELM-CSIC) in Málaga observed
the region of the sky containing the WXM error box for GRB
041016 (HETE trigger 3578) as part of the routinary observing
schedule. The field was not observed at optimum conditions
(air airmass, cirruses). A 30s exposure started at 4:40:00
UT (20.5s after beginning of the 33s long burst), i.e. covering
the last 12.5s of the burst's gamma ray activity. This image,
sets a R = 7.0 upper limit to the promt optical flash for GRB
041016."