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GCN Circular 22775

GRB 180613A: Possible IR afterglow
2018-06-14T01:45:46Z (6 years ago)
Antonio de Ugarte Postigo at IAA-CSIC <>
C. C. Thoene (HETH/IAA-CSIC), N. Tanvir (Univ. of Leicester), A. de Ugarte
Postigo (HETH/IAA-CSIC, DARK/NBI), D. A. Kann, L. Izzo (both
HETH/IAA-CSIC), G. Pugliese (API/U. Amsterdam), P. Schady (MPE) and D. Xu
(NAO/CAS) report on behalf of the Stargate consortium:

We observed the field of GRB 180613A (GCN 22769, Tohuvavohu et al.) with
HAWKI at the VLT (ESO, Paranal, Chile) starting on June 13, 2018, at 22:51
UT (7.25 hours after the burst). Imaging observations were obtained in J, H
and Ks filters with exposure times of 11-12 min under thin clouds but
excellent seeing conditions (around 0.4 arcsec) and preliminary reductions
provided by the observatory.

The object reported in GCN 22772 (Kann & Izzo) is clearly detected and
likely a foreground star. Inside the refined XRT error circle (GCN 22771,
Evans) we detect a faint source in all three bands at the coordinates
(errors +/-0.5 arcsec):

RA 14:06:04.89
DEC -43:04:19.6

The source seems to be slightly extended to the NW and a point-like source
at the SW end of it. This could possibly be the underlying host +
afterglow. Further observations are needed to determine a possible fading
of the source. Preliminary photometry gives J = 22.86 +/- 0.25 mag using
aperture photometry centered on the point-like part of the source and
compared to field stars from the 2MASS catalogue.

We acknowledge the excellent support from ESO staff, in particular Fr��d��ric
Vogt, Ivan Aranda and Stephane Brillant and enjoyed the great new option to
chat on Skype with the telescope during the observations.

[GCN OPS NOTE(14jun18):  Per author's request, the "days" in the 3rd line
was changed to "hours".]
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