A. de Ugarte Postigo (HETH/IAA-CSIC, DARK/NBI), D. A. Kann
L. Izzo, C. C. Thoene (HETH/IAA-CSIC), N. Castro-Rodriguez
(GTC, IAC, ULL), A. Marante, J. A. Melian (GTC) report:
We observed the field of GRB 170714A (D'Ai et al. GCN 21340), an
ULGRB or RTDE candidate (Kann et al., GCN 21345) with OSIRIS at
the 10.4m GTC telescope in La Palma (Spain). Observations consisted
in several short exposures in i and z filters. The observations were not
easy, as the field was located 30 deg away from the 68% illuminated
Moon, implying a very high background.
In the combined z-band frame, with mean epoch at 05:10:24 UT (16.75 hr
after the burst) we detect a single object within the refined XRT error box
(Evans et al. GCN 21341) which is not present in PanSTARRS imaging,
with coordinates (J2000):
and a magnitude of z(AB)=22.3+/-0.2, which we identify as the possible
GRB afterglow, although we cannot make any statement about
variability at this time. In our preliminary analysis we do not detect the
object in any other band, implying a possible strong reddening.
Further follow up, especially in NIR bands is encouraged.