TITLE:   GCN CIRCULAR
NUMBER:  13276
SUBJECT: GRB 120422A: Gemini-N detection of a supernova
DATE:    12/05/01 14:30:04 GMT
FROM:    Nial Tanvir at U.Leicester  <nrt3@star.le.ac.uk>

K. Wiersema (U. Leicester), A. Cucchiara (UCSC/UCO Lick),
A. J. Levan (U. Warwick), S. Rapoport, B. P. Schmidt (ANU), D. Bersier (LJMU),
D. Perley (Caltech), S. B. Cenko (UC Berkeley), N. R. Tanvir (U. Leicester)
report on behalf of a larger collaboration:

We observed the position of GRB 120422A (Troja et al., GCN 13243) using
the GMOS-N Spectrograph on the Gemini-North telescope. We acquired spectra
starting at 06:36 UT on 1 May 2012. We used the R400 grism, obtaining 4 x 1200
seconds exposure time, covering a wavelength range 4400 - 8670 A.

In addition to many narrow nebular lines from the host galaxy (Tanvir et
al. GCN 13251; Schulze et al. GCN 13257), the spectra show several broad
undulations in the continuum. The restframe positions of these features are
well matched to those seen in spectra of SN 1998bw at early times. We
therefore conclude that the rebrightening reported by Malesani et al. (GCN
13275) is consistent with being caused by a broad-lined type Ib/c supernova.

We thank Kristin Chiboucas for obtaining these observations.