[vsnet-grb-info 14666] GRB 140311A: further NOT observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  15980
SUBJECT: GRB 140311A: further NOT observations
DATE:    14/03/13 10:30:24 GMT
FROM:    Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst  <malesani at dark-cosmology.dk>

D. Malesani (DARK/NBI), P. D'Avanzo (INAF/Brera), Y. F. Martinez Osorio 
(NOT and Univ. Uppsala), report on behalf of the CIBO collaboration:

We observed the optical afterglow of GRB 140311A (Racusin et al., GCN 
15944; Xu et al., GCN 15947) with the Nordic Optical Telescope equipped 
with ALFOSC. A total exposure of 24 min was secured in the SDSS i band.

At a mean epoch of March 13.043 UT (1.16 days after the GRB), the 
optical counterpart is well detected with an AB magnitude i = 22.45 +- 
0.08, calibrated to several nearby SDSS stars. The position of the 
afterglow is (J2000):

RA = 13:57:13.29
Dec = +00:38:31.7

referenced to the USNO-B1 catalog (0.3" error).

Compared to the i-band value reported by Littlejohns et al. (GCN 15978), 
our measurement implies a decay index alpha = 0.81 +- 0.10 (Fnu propto 
nu^-alpha), consistent with the value reported by these authors.