GCN Circular 2595

D. A. Smith (NSF/U of Michigan) reports on behalf of the ROTSE collaboration:
  
The ROTSE-IIIa telescope (at SSO, Australia) responded rapidly to both the
intitial on-board alert and the final ground analysis alert distributed by
HETE-2 for GRB 040511 (HETE #3218, Dullighan et al., GCN Circ. #2588).  In both
cases, the first ROTSE-IIIa exposure began within 3.5 s of the alert time
stamp.  The final SXC localization was outside the field of view of the first
series of ROTSE-IIIa images, so those data are not included in this report.
The second series of images began at 15:11:34.57 UTC, ~2.2 h after the burst
trigger time.  The instrument responded automatically with a pre-programmed
sequence of ten 5-s and ten 20-s images, after which it recorded 44 60-s
images.  The first 60 images were co-added in sets of ten, reaching limiting
magnitudes of ~17.2 for the 5-s images and ~17.5 for the others.  (ROTSE-III
images are unfiltered, but calibrated to USNO A2.0 R-band.)  Comparison of
these images to the USNO catalogs and the DSS 2nd Generation R-band image
reveal no new sources.  The detected foreground sources are estimated to cover
~10-15% of the SXC error circle.

In short, ROTSE-IIIa provides the following approximate R-band upper limits
(the first column is the elapsed time to the middle of the co-added exposure):

Time from              Exp. Time            Upper Limit
Burst Trigger
(hours)                 (sec)
2.18                      50                    17.2
2.24                     200                    17.5
2.37                     600                    17.5
2.57                     600                    17.5
2.76                     600                    17.6
2.95                     600                    17.5