[vsnet-grb-info 9029] GRB 100316D: VLT/X-shooter observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  10512
SUBJECT: GRB 100316D: VLT/X-shooter observations
DATE:    10/03/17 03:05:25 GMT
FROM:    Paolo D'Avanzo at INAF-OAB  <paolo.davanzo at brera.inaf.it>

S.D. Vergani (GEPI-Obs. Paris), P. D'Avanzo (INAF-OAB), A.J. Levan (Univ.
Warwick), S. Covino (INAF-OAB), D. Malesani, J. Hjorth (DARK/NBI), L.A.
Antonelli (INAF-OAR) report on behalf of a larger collaboration:

We observed the field of GRB 100316D (Stamatikos et al., GCN 10496) with
the VLT equipped with the X-shooter spectrograph. Observations started on
2010 Mar 17 at 00:58 UT (~ 12 hours after the GRB). In the 100s
acquisition image, we detect an object inside the XRT error circle, at the
following position (J2000):

RA: 07:10:30.77
Dec: -56:15:20.7

(+/- 0.5"). The object has a magnitude R~21 (calibrated against USNO-B1.0)
and is very close (~3.5") to the DSS galaxy reported by Sakamoto et al.
(GCN 10511). In the X-shooter spectrum of this source we detect several
bright emission lines. Among these we have [OII], Hdelta, Hgamma, Hbeta,
[OIII], Halpha all at a common redshift of 0.059. At present, we cannot
say if this object (that might be a region of the nearby galaxy) is
related with GRB 100316D. Further analysis and observations are in
progress.

We caution that the above analysis (particularly the wavelength solution)
is preliminary. Reduction with updated calibrations is underway. We would
like to thank the ESO staff for their kind assistance, in particular
Thomas Rivinius, Alvaro Alvarez and Andres Pino