[vsnet-grb-info 2651] GRB 060111B: ROTSE-III Detection of Optical Counterpart Flare

[GCN Circulars]

TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  4488
SUBJECT: GRB 060111B: ROTSE-III Detection of Optical Counterpart Flare
DATE:    06/01/11 21:25:14 GMT
FROM:    Sarah Yost at U.Michigan  <sayost at umich.edu>

S.A. Yost, F. Yuan, H. Swan, C. Akerlof (U Mich), report on behalf of
the ROTSE collaboration:

ROTSE-IIId, located at the Turkish National Observatory at Bakirlitepe,
Turkey, responded to GRB 060111B (Swift trigger 176918). The first image
was at 20:16:12 UT, 29 s after the burst (9 s after the GCN notice
time). The unfiltered images are calibrated relative to USNO A2.0.

We detect an optical flare at the position of the UVOT optical
counterpart (GCN 4487). It was observed initially at 13.0 mag, fading at
least as rapidly as ~ t^-2.6. We detect it in 3 5-sec images and it has
faded to or below the limiting magnitude of 15.5 in the 4th image at 69
sec post-burst.


start UT    	mag     mlim(of image)
----------------------------------
20:16:12     13.0     15.2
20:16:52   >~15.5     15.5

A jpeg image is available at
http://www.rotse.net/images/gsb176918_3d00_img.jpg