[vsnet-grb-info 15041] Swift Trigger 600114: Optical spectroscopy from GTC

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  16335
SUBJECT: Swift Trigger 600114: Optical spectroscopy from GTC
DATE:    14/05/28 07:54:06 GMT
FROM:    Javier Gorosabel at IAA-CSIC  <jgu at iaa.es>

J.  Gorosabel  (IAA-CSIC/UPV-EHU),   A.  de  Ugarte Postigo (IAA-CSIC/DARK-NBI),  C.  Thöne  (IAA-CSIC), T.  Muñoz-Darias  (Oxford Uni.),  R. Sanchez-Ramirez (IAA-CSIC),  R. Scarpa (IAC-ULL), report on  behalf of  a larger collaboration.

We have obtained spectroscopic data  of the optical counterpart of the bright X-ray  source in  M31 (Barthelmy et  al.  GCNC 16332)  with the 10.4m GTC telescope.  Observations started  on May 28.17800 UT, 6.9 hr post  burst.  Three  600s spectra  where taken  with the  R1000B grism yielding a spectral  range between 3700 and 7700 A  at a resolution of ~1000.  The slit  was  positioned  within the  central  light of  the globular  cluster   that  is   probably  associated  with   the  event (FMZ2005-7).  A  preliminary reduction of the  spectra reveals several absorption lines,  including Na  I, the Balmer  series and Ca  II, all blue-shifted consistently  with the 427  km/s reported by Kang  et al. 2012 (ApJS,  199, 37).   A very preliminary  analysis shows  no excess with  respect   what  we  would  expect  from   the  globular  cluster emission. A deeper analysis is ongoing.