[vsnet-grb-info 13745] GRB 130603B: Second epoch of HST WFC/F160W imaging

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  15060
SUBJECT: GRB 130603B: Second epoch of HST WFC/F160W imaging
DATE:    13/08/03 11:26:03 GMT
FROM:    Edo Berger at Harvard  <eberger at cfa.harvard.edu>

W. Fong and E. Berger (Harvard) report:

"We inspected the second epoch of HST WFC3/F160W imaging of the short GRB
130603B obtained on 2013 July 3.24 UT.  Digital image subtraction relative
the first epoch (on 2013 June 13.15 UT) reveals that the near-IR point
source coincident with the afterglow position has faded away, confirming
our original suggestion that it is associated with GRB 130603B (Berger et
al. 2013 arXiv:1306.3960).  The subtraction also confirms our brightness
measurement, with m(F160W)=25.8 AB mag.  Coupled with an early steep
decline in the optical band based on additional Magellan/IMACS observations
at 32.2 hr post-burst, with r>24.8 AB mag (see also Cucchiara et al. 2013,
arXiv:1306.2028; Tanvir et al. 2013, arXiv:1306.4971) this confirms the
likely kilonova origin of this source."