Skip to main content
Introducing Einstein Probe, Astro Flavored Markdown, and Notices Schema v4.0.0. See news and announcements

GCN Circular 10036

Subject
GRB 091018: ROTSE-III Detection of Optical Counterpart
Date
2009-10-18T21:34:32Z (15 years ago)
From
Brad Schaefer at LSU <schaefer@grb.phys.lsu.edu>
B. E. Schaefer (Louisiana State) and S. B. Pandey (U Mich), report on
behalf of the ROTSE collaboration:

ROTSE-IIIc, located at the H.E.S.S. site at Mt. Gamsberg, Namibia,
responded to GRB 091018 (Swift trigger 373172, Stamatikos et al., GCN
10034). The first image was at 20:57:36.1 UT, 556.6 s after the burst
(11.1 s after the GCN notice time).  The unfiltered images are calibrated
relative to USNO A2.0. We detect a new object, not visible in the DSS
(second epoch), with coordinates:

     02:08:44.6      -57:32:53.6    (J2000), 

with positional uncertainty of 1" or better

start UT    	mag     mlim(of image)
----------------------------------
20:57:36.1     15.4     16.4 


With this, we confirm the optical afterglow reported in GCN 10034 as a
UVOT detection.  The source is rapidly fading.  A jpeg image is available 
at
http://www.rotse.net/images/gsb373172_3c01_img.jpg Note that the object
numbered 14 (in the lower of the two circles) is the candidate in
question.

Continuing observations are in progress.
Looking for U.S. government information and services? Visit USA.gov