[vsnet-grb-info 3705] GRB 060906: Early RAPTOR optical limits

[GCN Circulars]

TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  5539
SUBJECT: GRB 060906: Early RAPTOR optical limits
DATE:    06/09/06 22:01:25 GMT
FROM:    James Wren at LANL  <jwren at nis.lanl.gov>

J. Wren, W.T. Vestrand, P.R. Wozniak, R. White, S. Evans, and
J. Pergande of Los Alamos National Laboratory report:
 
The RAPTOR array of telescopes autonomously responded to Swift
trigger 228316.  Conditions were cloudy at our primary telescope
site but our wide-field RAPTOR-B small telescope array, located
at our secondary site, imaged the event under clear conditions.
Imaging began at 08:34:12.53 UTC (86.0 s after the trigger, 5.8 s
after receipt).  We do not detect the counterpart seen by the Swift
XRT (Racusin et al. GCN 5528) and P60 (Cenko et al. GCN 5529).
The initial unfiltered 5 s exposure yields a 3-sigma limiting
magnitude at the counterpart location of R=15.2 when calibrated
against the GSC 1.1 R-band.  This limit has not been corrected
for foreground galactic extinction.