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GCN Circular 8170

GRB 080903: ROTSE-III Optical Limits
2008-09-03T02:12:02Z (16 years ago)
Fang Yuan at ROTSE <>
F. Yuan (U Mich), W. Rujopakarn (Steward), H. Swan (U Mich), D.A.  
Smith (Guilford), T. Guver (U Arizona) report on behalf of the ROTSE  

ROTSE-IIId, located at the Turkish National Observatory at  
Bakirlitepe, Turkey, responded to GRB 080903 (Swift trigger 323542;  
Grupe et al., GCN 8169), producing images beginning 6.7 s after the  
GCN notice time. An automated response took the first image at  
01:12:47.7 UT, 24.4 s after the burst, and during the gamma-ray  
emission, under fair conditions. We took 10 5-sec, 10 20-sec and 30 60- 
sec exposures. These unfiltered images are calibrated relative to USNO  
A2.0 (R). Imaging is on going.

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. Individual images have  
limiting magnitudes ranging from 16.5-17.7; we set the following  
specific limits.

start UT       end UT      t_exp(s)   mlim   t_start-tGRB(s)  Coadd?
01:12:47.7   01:14:55.9       128     17.7           24.4       Y
01:15:04.6   01:19:42.4       277     18.3          161.3       Y
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