{
  "bibcode": "2022GCN.32800....1D",
  "body": "A. de Ugarte Postigo (OCA), L. Izzo (DARK/NBI), C. C. Thoene\n (ASU-CAS), J. P. U. Fynbo (DAWN/NBI), D. A. Kann (Goethe Univ.), \nJ. F. Agui Fernandez (IAA-CSIC), N. R. Tanvir (Leicester Univ.) report:\n\nWe have been spectroscopically monitoring the evolution of the \nextremely bright GRB 221009A (Swift detection: Dichiara et al., \nGCN 32632; Fermi GBM detection: Veres et al., GCN 32636) using \nOSIRIS at the 10.4m GTC telescope. In a spectrum combining data \ntaken on 16 and 17 October (at an average time of ~8 days after the \nburst), covering the spectral range between 3700 and 10000 AA, the \nemission is still clearly dominated by the afterglow. However, after \nsubtracting a model of the continuum, the spectrum shows undulations \ncharacteristic of a GRB-SN. In particular we identify broad features at \nsimilar wavelengths (after correcting for the redshift difference) as \nthose present in SN 1998bw, with somewhat larger velocities. This is \nindicative of the emergence of the associated supernova. Further \nfollow-up observations are planned.",
  "circularId": 32800,
  "createdOn": 1666178610000,
  "email": "deugarte@oca.eu",
  "subject": "GRB 221009A: Spectroscopic detection of emerging SN features",
  "submitter": "Antonio de Ugarte Postigo at OCA  <deugarte@oca.eu>",
  "eventId": "GRB 221009A"
}