TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  4664
SUBJECT: GRB 060204C: ROTSE-III Optical Limits 
DATE:    06/02/04 21:55:29 GMT
FROM:    Eli Rykoff at U of Michigan/ROTSE  <erykoff@umich.edu>

E.S. Rykoff (U Mich), S.A. Yost (U Mich), B. E. Schaefer (Louisiana 
State), F. Yuan (U Mich), T. Guver (U Istanbul), report on behalf of the 
ROTSE collaboration:

ROTSE-IIId, located at the Turkish National Observatory at Bakirlitepe, 
Turkey, responded to GRB 060204C (Swift trigger 180274, GCN 4663), 
producing images beginning 6.8 s after the GCN notice time. An automated 
response took the first image at 20:35:04.8 UT, 81.8 s after the burst, 
under windy conditions. We took 10 5-sec, 10 20-sec and 31 60-sec 
eposures. 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, for both single images and coadding into sets 
of 10. Individual images have limiting magnitudes ranging from 
16.1-17.7; we set the following specific limits.

start UT       end UT      t_exp(s)   mlim   t_start-tGRB(s)  Coadd?
--------------------------------------------------------------------
20:35:04.8   20:35:09.8         5     16.1           81.8       N
20:35:04.8   20:37:11.5       126     17.7           81.8       Y
20:37:20.2   20:41:56.3       276     18.2          217.2       Y