TITLE:   GCN CIRCULAR
NUMBER:  6647
SUBJECT: GRB 070721B : Faulkes Telescope South observations
DATE:    07/07/21 18:43:02 GMT
FROM:    Andrea Melandri at Liverpool John Moores U  <axm@astro.livjm.ac.uk>

A. Melandri, (Liverpool JMU), C. Guidorzi (Uni-Bicocca/INAF-OAB),
I.A. Steele, C.G. Mundell, D. Carter, R.J. Smith, C.J. Mottram,
D.F. Bersier, S. Kobayashi, M.J. Burgdorf, M.F. Bode (Liverpool JMU),
A. Gomboc (Ljubljana), P. O'Brien, E. Rol, N. Bannister (Leicester)
report

We observed the field of GRB 070721B (trigger=285654, Ziaeepour
et al., GCN 6640) with the Faulkes Telescope South on 2007 Jul 21
starting at 16:01:21 UT (~5.45 hours after the trigger).

We do not detect any new source inside the refined XRT error circle
(Beardmore et al., GCN 6646) and we do not detect the UVOT candidate
reported by Schady et al. (GCN 6641) in our optical images.

We can set an upper limit for this burst of R>19.3 and I>17.8
@ 6.4 and 6.2 hours after the trigger, respectively.