TITLE:   GCN CIRCULAR
NUMBER:  31739
SUBJECT: ZTF22aabjpxh/AT2022cva (GRB 220219B): evidence of supernova in LBT spectra
DATE:    22/03/11 14:41:55 GMT
FROM:    Andrea Rossi at INAF  <andrea.rossi@inaf.it>

A. Rossi, E. Pian, F. Cusano, E. Maiorano, E. Palazzi (INAF-OAS) on 
behalf of the CIBO collaboration, and S. Belkin (IKI, HSE) report :

We report the results of the spectroscopic follow-up observations of 
ZTF22aabjpxh/AT2022cva, the afterglow of GRB 220219B (Ho et al., GCN 
31619; Kim  et al., GCN 31628; Hu et al., GCN 31639; Belkin et al., GCNs 
31643, 31683; Pasham et al., GCN 31635; Beardmore et al., GCN 31644; 
Tsvetkova et al., GCN 31646) at z=0.293 (Fremling et al., GCN 31629). 
The optical spectra were obtained with the Multi-Object Double 
Spectrographs (MODS) instrument mounted on the 2x8.4-m LBT telescope 
(Mt. Graham, AZ, USA) at ~11 UT on 2021-03-07, ~16 days (i.e. ~12 
rest-frame days) after the burst trigger. The spectra covers the 
wavelength range 3200-10000 AA, and we obtained a total of 6 exposures 
of 900s. The resulting spectrum has been corrected for Galactic 
extinction (A_V = 0.025 mag).

The slit was place in order to cover both the host galaxy and the GRB 
position. In addition to the host spectra, a second trace is well 
visible in the 2D image of the spectrum although superimposed to the one 
of the host galaxy. Its low S/N extracted spectrum shows features 
similar to those exhibited by XRF-associated SN2006aj at a similar phase 
(Mazzali et al. 2006, Nature, 442, 1018). This confirms the bump 
observed by Belkin et al. (GCN 31736) as due to the emerging 
contribution of the SN.

We acknowledge the excellent support from the LBTO, in particular B. 
Rothberg and J. Williams, and from the LBT-INAF, particularly E. Marini 
in obtaining these observations.