[vsnet-grb-info 21863] GRB 190311A: NOT optical counterpart

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  23962
SUBJECT: GRB 190311A: NOT optical counterpart
DATE:    19/03/12 21:47:13 GMT
FROM:    Jonatan Selsing at DARK/NBI  <jselsing at dark-cosmology.dk>

J. Selsing (DAWN/NBI), Z.P. Zhu (NAOC), D. Xu (NAOC), D. Malesani 
(DAWN/NBI, DARK/NBI), D. Nespral (IAC), D. Gandolfi (Univ. Turin), and 
J. Telting (NOT), report on behalf of a larger collaboration:

We have observed the optical afterglow of GRB 190311A (Troja et al., 
GCN 23946; Goad et al., GCN 23950; Veres & Meegan, GCN 23953) with the 
2.5-m Nordic Optical Telescope (NOT). We have obtained an r+z imaging 
sequence using the ALFOSC instrument, with 4x300 and 5x300 s exposure in 
the r and z band, respectively. Imaging observations began 9.4 hr after 
the BAT trigger.

In the images we clearly detect the optical counterpart of GRB 190311A, 
as previously reported (Zhu et al., GCN 23948; Pozanenko et al., GCN 
23947; Gorbovskoy et al., GCN 23949; Belkin et al., GCN 23951; Mao et 
al., GCN 23954; Peris & Fernandez-Soto, GCN 23959).

We calibrate the photometric zeropoints against the Pan-STARRS catalog
and derive the following magnitudes for the optical counterpart:

r = 21.88 +- 0.03 AB mag
z = 21.26 +- 0.04 AB mag

The source is centred at the position:

RA (J2000.0) = 14:08:15.726
DEC (J2000.0) = +53:30:02.74

with the astrometric solution calibrated against the 2MASS catalog.