GCN Circular 2595
Subject
GRB 040511: ROTSE-III Rapid Optical Upper Limits
Date
2004-05-13T16:23:16Z (21 years ago)
From
Don Smith at U michigan <dasmith@rotse2.physics.lsa.umich.edu>
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