[vsnet-grb-info 14073] Swift Trigger 575905: ROTSE-III Optical Limits

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  15387
SUBJECT: Swift Trigger 575905: ROTSE-III Optical Limits
DATE:    13/10/26 08:01:52 GMT
FROM:    Farley V. Ferrante at Southern Methodist U/ROTSE  <fferrante at smu.edu>

F. V. Ferrante, G. Dhungana, and R. Kehoe (SMU) report on behalf of the ROTSE GRB team:


The 0.45-m ROTSE-IIIb, located at McDonald Observatory, Texas, responded to Swift trigger 575905 (Cenko et al., GCN 15384), producing images beginning 7.7 s after the GCN notice time. An automated response took the first image at 06:40:53.8 UT, 81.0 s after the burst, under fair conditions. We took 10 5-sec, 10 20-sec and 60 60-sec exposures. These unfiltered images are calibrated relative to USNO A2.0. Imaging is on going.


Comparison to the DSS (second epoch) reveals no new sources within the 3-sigma Swift/BAT error circle, for both single images and coadding into sets of 10. Individual images have limiting magnitudes ranging from 13.3-16.9; we set the following specific limits.

start UT       end UT      t_exp(s)   mlim   t_start-tGRB(s)  Coadd?
--------------------------------------------------------------------
06:40:53.8   06:42:40.9       107     16.4           81.0       Y