[vsnet-grb-info 13667] GRB 130702A: further TNG observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  14984
SUBJECT: GRB 130702A: further TNG observations
DATE:    13/07/04 15:44:22 GMT
FROM:    Paolo D'Avanzo at INAF-OAB  <paolo.davanzo at brera.inaf.it>

P. D'Avanzo (INAF-OAB), V. D'Elia (ASI/ASDC), G. Tagliaferri, A. Melandri (INAF-OAB), D. Malesani (DARK/NBI), M. Della Valle (INAF-OAC), E. Pian (SNS) report on behalf of the CIBO collaboration:

We observed the optical counterpart of the Fermi GRB 130702A (Cheung et al. GCN 14971; Collazzi et al. GCN 14972) with the Italian 3.6m TNG telescope located in Canary Islands, equipped with the DOLoRes imager.

In addition to what reported in D'Avanzo et al. (GCN 14977), further observations were carried out between Jul 3.955 UT and Jul 4.022 UT (1.95-2.02 days after the Fermi GBM trigger).

The optical afterglow is clearly detected in the SDSS g, r, and i bands with the following magnitudes:

g=19.3
r=19.1
i=19.0

calibrated against nearby SDSS stars.

We also obtained a 2400 seconds spectrum with the LR-B grism, covering the wavelength range 3900-8200 AA with a resolution of R~600. The spectrum has a high S/N and shows a blue continuum nearly featureless. Very faint emission lines can be interpreted as [OII] 3727.5, [OIII] 4959.0/5006.8 and Halpha 6562.8 at a common redshift of 0.145, consistent with what reported by Mulchaey et al. (ATel 5191) for the optical afterglow spectrum and by Leloudas et al. (GCN circ. 14983) for the spectrum of the nearby SDSS galaxy.


We acknowledge the TNG staff for excellent support, in particular G. Andreuzzi and G. Mainella.