TITLE:   GCN CIRCULAR
NUMBER:  10543
SUBJECT: Emerging Supernova in the Afterglow of GRB 100316D
DATE:    10/03/24 13:37:52 GMT
FROM:    Filomena Bufano at INAF-Osb Astro di Padova  <filomena.bufano@oapd.inaf.it>

F. Bufano, S. Benetti, E. Cappellaro, INAF Osservatorio Astronomico di  
Padova (INAF-OAPd); S. Covino, INAF Osservatorio Astronomico di Brera  
(INAF-OABr); S. Vergani, P.Goldoni, GEPI (Observatoire de Paris) - APC  
(Université Paris 7); M. Della Valle, INAF Osservatorio di  
Capodimonte; E. Pian, INAF Osservatorio Astronomico di Trieste; S.  
Campana, G.Tagliaferri, INAF-OABr; D.Malesani, J. Fynbo, Dark  
Cosmology Centre; M. Turatto, INAF Osservatorio Astronomico di  
Catania; F.Patat, European Southern Observatory (ESO) and P. Mazzali,  
INAF-OAPd  report on behalf of a larger colaboration that a high-dispersion
optical spectrum (range  350-900 nm, resolution 0.02 nm) of the afterglow
associated to GRB  100316D (cf. GCN 10496) was obtained with the VLT telescope  
(+XShooter) at ESO-Paranal on March 23.04 UT. The spectrum of  the  
source located at R.A.=07:10:31.8 and Decl.=-56:15:20.2, J2000.0 (as  
measured on the XShooter acquisition image) shows very broad bumps   
with peaks measured at about 430nm and 670nm reminiscent of an  
emerging broad line type Ic supernova (in agreement with Chornock et al,
GCN 10541). Indeed, above 600 nm the spectrum of this source
shows some similarities with that of SN 1998bw (Patat et al. 2001,
ApJ, 555, 900) taken 7 days after outburst.

There are however major differences  with the spectrum of this  
transient, showing a significant flux deficiency in the range  
450-550nm in comparison with SN 1998bw .

[GCN OPS NOTE(24mar10): Per author's request, the parenthetical
comment "(in agreement with Chornock et al, GCN 10541)"
was added.]