TITLE:   GCN CIRCULAR
NUMBER:  22345
SUBJECT: GRB 180115A: NOT detection of optical counterpart
DATE:    18/01/15 22:47:53 GMT
FROM:    Zach Cano at U of Iceland  <zewcano@gmail.com>

Z. Cano (HETH/IAA-CSIC), K. E. Heintz (Univ. Iceland & DARK/NBI), A. de
Ugarte Postigo (HETH/IAA-CSIC, DARK/NBI), I. Marquez & S. Cazzoli
(IAA-CSIC) report on behalf of a larger collaboration:

We observed the field of GRB 180115A (Cannizzo et al.; GCN Circ. 22335)
with the 2.5-m Nordic Optical Telescope equipped with ALFOSC, starting at
19:40:26 UT on 15 January 2017.  We obtained 3x300 s in the r-band.  In our
co-added image a faint, new object is detected in the enhanced XRT error
circle (Goad et al.; GCN Circ. 22337), with an apparent magnitude of r =
21.3 +- 0.1, at a mean post-explosion epoch of +15.53 hours.  The
calibration was performed using local Pan-STARRS standards in the GRB
field.  This apparent magnitude is not corrected for foreground extinction.