TITLE:   GCN CIRCULAR
NUMBER:  25261
SUBJECT: LIGO/Virgo S190728q: AT2019lzc 10.4m GTC spectroscopy
DATE:    19/08/04 09:00:46 GMT
FROM:    Alberto J. Castro-Tirado at IAA-CSIC  <ajct@iaa.es>

A. F. Valeev (SAO-RAS), A. J. Castro-Tirado, Y.-D. Hu and E. 
Fernandez-Garcia (IAA-CSIC), V. V. Sokolov (SAO-RAS), I. Carrasco and A. 
Castellon (UMA) and N. Castro-Rodriguez (GRANTECAN, IAC, ULL), on behalf 
of a larger collaboration, report:

Following the detection of AT2019lzc (Huber et al., GCN 25224, Andreoni 
et al., GCNC 24235) within the error area of the GW event S190728q (LVC, 
GCNC 25187), we obtained imaging and optical spectra covering the range 
3700-7500 A with the 10.4m GTC telescope equipped with OSIRIS in La 
Palma (Spain) starting on Aug 4, 04:30 UT.

AT2019lzc magnitude on Aug 4, 04:30 UT was measured to be r = 20.9 +/- 
0.1. The AT2019lzc 1200s spectrum displays broad lines and is consistent 
with a SN Ia at about 20 days post maximum at the nearby host galaxy 
redshift (z =  0.207 +/- 0.005, based on the narrow emission lines from 
the galaxy).

Therefore AT2019lzc is unrelated to the GW event S190728q.