[vsnet-grb-info 20586] GRB 180504A: NOT afterglow candidate

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  22684
SUBJECT: GRB 180504A: NOT afterglow candidate
DATE:    18/05/05 07:05:30 GMT
FROM:    Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst  <malesani at dark-cosmology.dk>

D. Malesani (DAWN/NBI and DARK/NBI) and Illa R. Losada (NOT, Nordita, 
Stockholm Univ.) report on behalf of a larger collaboration:

We observed the field of GRB 180504A (Lien et al., GCN 22682) with the 
Nordic Optical Telescope equipped with the AlFOSC camera. The field has 
a bad visibility from La Palma, and observations were carried out at 
large airmass (~2) and straddling twilight. The average seeing was 1.5".

Coincident with the UVOT-enhanced position reported by Evans (GCN 
22683), we note the presence of a faint source, at a position (J2000; 
0.5" error):

RA = 22:04:34.61
Dec = -14:39:30.0

We note that the automatically reported un-enhanced XRT position 
(available from http://www.swift.ac.uk/xrt_positions/) is at the time of 
writing significantly different from the one quoted in the GCN, and 
would not include our afterglow candidate.

Photometry of the candidate against nearby stars from the Pan-STARRS 
survey yields r = 22.5 +/- 0.3 (AB) at a mean time 2018 May 5.222 UT 
(9.57 hr after the trigger)

Further observations are planned.