GCN Circular 32800
Subject
GRB 221009A: Spectroscopic detection of emerging SN features
Date
2022-10-19T11:23:30Z (2 years ago)
From
Antonio de Ugarte Postigo at OCA <deugarte@oca.eu>
A. de Ugarte Postigo (OCA), L. Izzo (DARK/NBI), C. C. Thoene
(ASU-CAS), J. P. U. Fynbo (DAWN/NBI), D. A. Kann (Goethe Univ.),
J. F. Agui Fernandez (IAA-CSIC), N. R. Tanvir (Leicester Univ.) report:
We have been spectroscopically monitoring the evolution of the
extremely bright GRB 221009A (Swift detection: Dichiara et al.,
GCN 32632; Fermi GBM detection: Veres et al., GCN 32636) using
OSIRIS at the 10.4m GTC telescope. In a spectrum combining data
taken on 16 and 17 October (at an average time of ~8 days after the
burst), covering the spectral range between 3700 and 10000 AA, the
emission is still clearly dominated by the afterglow. However, after
subtracting a model of the continuum, the spectrum shows undulations
characteristic of a GRB-SN. In particular we identify broad features at
similar wavelengths (after correcting for the redshift difference) as
those present in SN 1998bw, with somewhat larger velocities. This is
indicative of the emergence of the associated supernova. Further
follow-up observations are planned.