[vsnet-grb-info 4600] GRB 070429B: ROTSE-III Optical Limits

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  6359
SUBJECT: GRB 070429B: ROTSE-III Optical Limits
DATE:    07/04/29 03:56:35 GMT
FROM:    Brad Schaefer at LSU  <schaefer at grb.phys.lsu.edu>

B. E. Schaefer (Louisiana State), W. Rujopakarn (U Mich), E.S. Rykoff (U 
Mich), report on behalf of the ROTSE collaboration:

ROTSE-IIIc, located at the H.E.S.S. site at Mt. Gamsberg, Namibia,
responded to the short-burst GRB 070429B (Swift trigger 277582; Markwardt
et al. GCN 6358), producing images beginning 7.9 s after the GCN notice
time. An automated response took the first image at 03:09:30.9 UT, 26.5 s
after the burst, under excellent conditions. We took 10 5-sec, 10 20-sec
20 60-sec exposures, and observations are continuing. These unfiltered
images are calibrated relative to USNO A2.0 (R).

Comparison to the DSS (second epoch) reveals no new sources within the 
3-sigma BAT error circle and within the error circle for the possible XRT 
source, for both single images and coadding into sets of 10; the field is 
not crowded. Individual images have limiting magnitudes ranging from 
15.5-17.5; we set the following specific limits.

start UT end UT t_exp(s) mlim t_start-tGRB(s) Coadd?
--------------------------------------------------------------------
03:09:30.9 03:09:35.9 5 15.5 26.5 N
03:09:30.8 03:10:56.5 85 17.3 26.4 Y
03:27:43.5 03:39:11.4 687 18.5 1119.1 Y