TITLE:   GCN CIRCULAR
NUMBER:  18965
SUBJECT: GRB 160131A: TNG spectroscopic observations and redshift
DATE:    16/01/31 22:10:53 GMT
FROM:    Paolo D'Avanzo at INAF-OAB  <paolo.davanzo@brera.inaf.it>

D. Malesani (DARK/NBI), V. D'Elia (INAF/OAR and ASI/ASDC), P. D'Avanzo, A. Melandri (INAF-OAB), L. A. Antonelli (INAF/OAR and ASI/ASDC), L. Di Fabrizio, G. Mainella (INAF/TNG) report on behalf of the CIBO collaboration:

Following the observations reported in Melandri et al. (GCN 18961), we carried out further observations of the optical afterglow of GRB 160131A (Page et al., GCN 18951) with the 3.6m TNG telescope equipped with the DOLoRes camera in spectroscopic mode. A spectrum was acquired with the LR-B grism covering the range between 3500 and 8000 AA. The observation consisted of a single 1200 s exposure, starting on 2016 Jan 31 at 20:12 UT.

A preliminary analysis of the spectrum (based on archival calibration files) shows clearly the continuum with several absorption features due to Fe II, Mg II and Mg I at a common redshift of 0.97, which we propose as the redshift of the GRB.


We acknowledge support from the TNG visiting astronomer Ennio Poretti.