[vsnet-grb-info 13651] Fermi394416326: FTN detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  14968
SUBJECT: Fermi394416326: FTN detection
DATE:    13/07/03 10:02:32 GMT
FROM:    Cristiano Guidorzi at Ferrara U,Italy  <guidorzi at fe.infn.it>

C. Guidorzi (Ferrara U.), C.G. Mundell, I.A. Steele (LJMU),
on behalf of a large collaboration report:

On 2013 July 03 (09:03:30 UT) we began observing the field of the
possible optical afterglow of Fermi394416326 (Singer GCN Circ. 14967)
with the 2-m Faulkes Telescope North in Hawaii.
Observations were carried out using the BVRi filters.
We clearly detect the optical counterpart discovered by
Singer et al. with the following magnitudes

Time from GRB   Filter  Exposure[s]    Magnitude
(days)
----------------------------------------------------
1.38            i'      100            18.61 +- 0.07
1.38            R       120            18.46 +- 0.05
----------------------------------------------------

The calibration was performed using the i' magnitudes of
SDSS catalogue field stars and the R magnitudes obtained
using the transformations by Jordi et al (2006).