GCN Circular 9102

B. E. Schaefer (Louisiana State), F. Yuan (U Mich), report on behalf of 
the ROTSE collaboration:

ROTSE-IIIa, located at Siding Spring Observatory, Australia, responded to
GRB 090407 (Swift trigger 348650; H. Ziaeepour et al., GCN 9101
Loading...
 
 ),
producing images beginning 8.8 s after the GCN notice time. An automated
response took the first image at 10:29:05.8 UT, 40.2 s after the burst,
and during the gamma-ray emission, under fair conditions. We took 10
5-sec, 10 20-sec and 33 60-sec exposures. These unfiltered images are
calibrated relative to USNO A2.0 (R). Imaging is on going but the 
source is getting low.

Comparison to the DSS (second epoch) reveals no new sources within the 
3-sigma Swift/BAT error circle or the XRT error circle, for both single 
images and coadding into sets of 10; the field is not crowded. Individual 
images have limiting magnitudes ranging from 13.9-15.5; we set the 
following specific limits.

start UT       end UT      t_exp(s)   mlim   t_start-tGRB(s)  Coadd?
--------------------------------------------------------------------
10:29:05.8   10:29:10.8         5     14.1           40.2       N
10:29:05.8   10:31:19.0       133     16.1           40.2       Y