TITLE:   GCN CIRCULAR
NUMBER:  29306
SUBJECT: GRB 201015A: evidence of supernova in LBT spectra
DATE:    21/01/17 02:05:04 GMT
FROM:    Andrea Rossi at INAF  <andrea.rossi@inaf.it>

A. Rossi (INAF/OAS), S. Benetti (INAF-Padova), E. Palazzi (INAF/OAS), P. 
D'Avanzo (INAF-OAB), V. D'Elia (SSDC), and M. De Pasquale report on 
behalf of the CIBO collaboration:

We report the results of the photometric and spectroscopic follow-up of 
GRB 201015A (D'Elia et al. GCN 28632) at z = 0.42 (Izzo et al. GCN 
28661, de Ugarte Postigo et al. GCN 28649) obtained with the 
Multi-Object Double Spectrographs (MODS) instrument mounted on the 
2x8.4-m LBT telescope (Mt Graham, AZ, USA). Data were obtained at the 
mid time of 04:00 UT on 2020-11-13, ~28.8 days after the burst trigger.

Spectroscopy of the source was obtained for a total of 8x900 s, covering 
the wavelength range 3200-10000 AA. All the spectra have been corrected 
for the Galactic extinction (A_V = 0.93). The low S/N spectrum shows a 
peak around 5400 AA (rest frame) and is consistent with type Ic-BL 
supernova spectra around maximum light, in agreement with the results 
presented by Pozanenko et al. (GCN 29033).

Together with the spectroscopy we also obtained g and r-band imaging of 
the supernova, which thanks to the good seeing of 0.6" it is separated 
enough from the host galaxy to avoid contamination. We find r=23.5+-0.1 
for the SN and r=22.9+-0.2 for the host galaxy, calibrated against 
Pan-STARRS field stars.

We acknowledge the excellent support from the LBTO in particular D. 
Thompson, and from the LBT-INAF staff, particularly S. Paiano, F. 
Cusano, D. Paris and L. Cassarà in obtaining and reducing these 
observations.