[vsnet-grb-info 13661] GRB 130702A: NOT optical observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  14978
SUBJECT: GRB 130702A: NOT optical observations
DATE:    13/07/04 01:08:19 GMT
FROM:    Steve Schulze at U of Iceland  <sts30 at hi.is>

S. Schulze (PUC, MCSS), D. Xu (DARK/NBI), D. A. Kann (TLS Tautenburg), D. Malesani (DARK/NBI), S. Geier (NOT, DARK/NBI), P. Jakobsson (U. Iceland) report on behalf of a larger collaboration:

We observed the field of GRB 130702A (Singer et al., GCN 14967; Cheung et al., GCN 14971; Collazzi et al., GCN 14972) with 2.5m the Nordic Opitcal Telescope (NOT) equipped with ALFOSC. We obtained 1 x 120 s each in the r' and i' bands. Observations started at 23:36:59 UT on July 03 (i.e., 47.53 hrs after the burst).

The source reported in Singer et al. (GCN 14967) is clearly detected in both images. It has an r'-band magnitude of 19.13 +/- 0.01 mag  and an i' band magnitude of 18.82 +/- 0.01 mag (AB magnitude). The mid-exposure times are 47.5432 and 47.5900 hrs after trigger in r' and i',. The source faded by ~0.4 mag with respect to Singer et al. (GCN 14967). We create a light curve using the Rc/r' data of of Singer et al. (GCN 14967), Guidorzi et al. (GCN 14968) and Xu et al. (GCN 14975), and find a slope of alpha = 0.58, in agreement with that of Singer et al. Compared to all known GRB afterglows, the afterglow of GRB 130702A is among the brightest, of similar brightness as that of GRB130427A at the time of our observation (Xu et al. 2013, arXiv:1305.6832).

Calibration was done against SDSS J142915.86+154510.0 and SDSS J142911.60+154535.1 from SDSS DR9. We did not correct for Galactic foreground extinction.