TITLE: GCN CIRCULAR NUMBER: 13106 SUBJECT: GRB 120326A: ROTSE-III Optical Limits DATE: 12/03/26 01:47:12 GMT FROM: Wiphu Rujopakarn at U AZ/Steward W. Rujopakarn (Steward) and H. Flewelling (IfA/Hawaii) report on behalf of the ROTSE collaboration: ROTSE-IIId, located at the Turkish National Observatory at Bakirlitepe, Turkey, responded to GRB 120326A (Swift trigger 518626; Siegel et al., GCN 13105), producing images beginning 9.9 s after the GCN notice time. An automated response took the first image at 01:20:51.9 UT, 22.6 s after the burst, under fair conditions. We took 10 5-sec, 10 20-sec and 10 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 14.7-16.7; we set the following specific limits. start UT end UT t_exp(s) mlim t_start-tGRB(s) Coadd? -------------------------------------------------------------------- 01:20:51.9 01:20:56.9 5 14.7 22.6 N 01:20:51.9 01:22:59.9 128 16.3 22.6 Y