[vsnet-grb-info 16883] GRB150818A: NOT imaging

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  18164
SUBJECT: GRB150818A: NOT imaging 
DATE:    15/08/19 01:04:40 GMT
FROM:    Steve Schulze at U of Iceland  <sts30 at hi.is>

S. Schulze (PUC, MAS), J. P. U. Fynbo (DARK, NBI), T. Kruehler (MPE), D. Malesani, (DARK/NBI), I. V. Rasmussen, J. L. Marcher, L. L. Thomson (NBI), A. Djupvik (NOT), B. Milvang-Jensen (DARK/NBI) and P. Jakobsson (U Iceland) report on behalf a larger collaboration:

We observed the field of GRB 150818A (D'Elia et al., GCN 18152) with the Nordic Optical Telescope (NOT) equipped with ALFOSC. We obtained a 180 s and a 3x300 s image in R band. Observations started at 21:34 UT on August 18 (i.e. 9.62 hr after the burst).

We clearly detect the source reported in Marshall et al. (GCN 18155) and McCauley et al. (GCN 18161). We measure R=20.86 +/- 0.08 mag calibrated against several USNO stars. This value is not corrected for foreground extinction. 

Given the lack of evidence for variability (McCauley et al., GCN 18161), the association of this object with GRB 150818A remains unclear.