[vsnet-grb-info 14824] GRB140419A: NOT optical observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  16138
SUBJECT: GRB140419A: NOT optical observations
DATE:    14/04/21 17:59:57 GMT
FROM:    Dong Xu at DARK/NBI  <dong.dark at gmail.com>

D. Xu (DARK/NBI), T. Kruehler (ESO), N. Tanvir (U. Leicester), F.
Taddia, C. Fremling (Stockholm U.) report on behalf of a larger
collaboration:

We observed the optical afterglow of GRB 140419A (Marshall et al., GCN
16118; Zheng et al., GCN 16119; Kuin et al., GCN 16123) using the 2.5
Nordic Optical Telescope equipped with ALFOSC. We obtained 4x300s,
3x300s, 4x200s frames in the SDSS g-, r-, and i-filters, respectively,
with floating clouds, starting at 23:10 UT on 2014-04-20 .

Photometry is calibrated with nearby SDSS stars, and results are as follows:

Tmid-T0(hr)        Mag       MagErr
   43.24              >22.5
   43.54              23.16      0.15
   43.86              >20.3

Compared with previous measurements (e.g., from RATIR and KAIT), the
afterglow may be decaying more quickly.