A. J. Castro-Tirado (IAA-CSIC), A. F. Valeev and V. V. Sokolov
(SAO-RAS), Y.-D. Hu and E. Fernandez-Garcia (IAA-CSIC), I. Carrasco and
A. Castellon (UMA), P. Zarco-Villegas (SMA), X.-Y. Li (NIAOT) and P.
Pessev (GRANTECAN, IAC, ULL), on behalf of a larger collaboration,
Following the detection of AT2019lzt (Andreoni et al., GCNC 24235)
within the error area of the GW event S190728q (LVC, GCNC 25187), we
obtained imaging and optical spectra (1200s) covering the range
3700-7500 A with the 10.4m GTC telescope equipped with OSIRIS in La
Palma (Spain) starting on Aug 2, 04:15 UT.
AT2019lzt magnitude on Aug 2, 03:50 UT was measured to be r = 21.13 +/-
0.02. The AT2019lzt spectrum (broad lines) is consistent with a SN Ia at
4 days post maximum at the nearby host galaxy redshift (z = 0.193 +/-
0.001, based on the narrow emission lines from the galaxy).
Therefore AT2019lzt is unrelated to the GW event S190728q.