[vsnet-grb-info 20173] GRB 171222A: NOT Optical Afterglow

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  22269
SUBJECT: GRB 171222A: NOT Optical Afterglow
DATE:    17/12/23 01:06:51 GMT
FROM:    Daniel Perley at Liverpool JMU  <d.a.perley at ljmu.ac.uk>

D. A. Perley (LJMU), D. Malesani (DARK/NBI), K. Heintz (Univ. Iceland,
DARK/NBI), A. de Ugarte Postigo (IAA-CSIC, DARK/NBI), and J. J. Lehiten
(MPS) report on behalf of a larger collaboration:

We obtained observations of GRB 171222A (Racusin et al., GCN 22265)
using StanCam on the Nordic Optical Telescope, beginning at 00:08:31 UT
on 2017-12-23.  Imaging was obtained in both R and I bands.

In the raw images we identify an optical source, not visible in
pre-imaging from Pan-STARRS, at the following location within the XRT
error circle (Osborne et al. GCN 22266):

RA = 09:53:06.73
Dec = +35:37:35.5

We suggest that this source is the optical afterglow of GRB 171222A.
Provisional photometry relative to nearby USNO stars gives a magnitude
of R = 21.44 +/- 0.09 (at 7.67 hours after the GRB trigger).

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