TITLE:   GCN CIRCULAR
NUMBER:  19601
SUBJECT: GRB 160625B: TNG redshift confirmation
DATE:    16/06/27 09:51:06 GMT
FROM:    Valerio D'Elia at ASDC  <delia@asdc.asi.it>

V. D’Elia (INAF-OAR/ASI-ASDC), A. Melandri (INAF-OAB) and D. Malesani (DARK/NBI) report on behalf of the CIBO collaboration:

We observed the afterglow of GRB 160625B (Dirirsa et al., GCN 19580) with the TNG equipped with DOLORES and the LR-B grism. The spectrum was acquired on 2016-06-26 and covers the range between 3000 and 7800 AA. The observation consisted of 2400 s exposure, starting at 23:04:20.836 (24 hr after the trigger).

The optical counterpart is clearly detected in the acquisition images with a magnitude r = 19.0 +/- 0.3 at the position reported by Troja et al. (GCN 19588) and Oates and D'Aì (GCN 19589).

The spectrum shows a clear continuum. We detect absorption features consistent with Mg I, Mg II, Mn II and Fe II lines a redshift of z = 1.41 +/- 0.01, thus confirming the redshift reported by Xu et al. (GCN 19600).

We thanks the TNG staff for excellent support, in particular Luca di Fabrizio and Albar Garcia.