[vsnet-grb-info 23622] LIGO/Virgo S190910d: AT2019pvu, AT2019pvv, AT2019pvz and AT2019pwa 10.4m GTC spectroscopy

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  25721
SUBJECT: LIGO/Virgo S190910d: AT2019pvu, AT2019pvv, AT2019pvz and AT2019pwa 10.4m GTC spectroscopy
DATE:    19/09/10 23:31:49 GMT
FROM:    Alberto J. Castro-Tirado at IAA-CSIC  <ajct at iaa.es>

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) and J. Font Serra (GRANTECAN, IAC, ULL), on behalf of 
a larger collaboration, report:

Following the detection of ZTF19abyfhov/AT2019pvu, 
ZTF19abyfhaq/AT2019pvv, ZTF19abyfbii/AT2019pvz and 
ZTF19abyfazm/AT2019pwa (Anand et al., GCN 25706) within the error area 
of the GW event S190910d (LVC, GCNC 25695), we obtained imaging and 
optical spectra covering the range 3700-10000 A with the 10.4m GTC 
telescope equipped with OSIRIS in La Palma (Spain) starting on Sep 10, 
20:25 UT.

For AT2019pvu, a magnitude r = 20.33 +/- 0.05 on Sep 10, 20:58 UT is 
derived.  Cross-correlating the transient spectrum (broad lines) with 
supernova template spectra in SNID (Blondin & Tonry, 2007), we find
a good match to the spectra of SNIa at redshift z = 0.133 +/- 0.001.

For AT2019pvv, a magnitude r = 21.08 +/- 0.05 on Sep 10, 22:14 UT is 
derived. The spectrum shows a faint H-alpha line in emission at z = 0 
but the low S/N ratio prevents a more precise classification at this 
stage.

For AT2019pvz, a magnitude r = 20.26 +/- 0.05 on Sep 10, 20:27 UT is 
derived. The spectrum is consistent with that of a SN Ia at the nearby 
host galaxy redshift z = 0.1286 +/- 0.0005 (based on H-alpha, H-beta, [O 
III] and others narrow emission lines).

For AT2019pwa, a magnitude r = 18.38 +- 0.03 on Sep 10, 21:31 UT is  
derived. The spectrum displays a blue continuum with the Ca II H&K 3934 
A and 3969 A doublet in absorption at z = 0 being the only clear 
features, which supports the object being a cataclysmic variable in our 
Galaxy, in agreement with Perley and Copperwheat (GCNC 25720).

Therefore we consider ZTF19abyfhov/AT2019pvu, ZTF19abyfhaq/AT2019pvv, 
ZTF19abyfbii/AT2019pvz and ZTF19abyfazm/AT2019pwa to be unrelated to the 
GW event S190910d.