TITLE:   GCN CIRCULAR
NUMBER:  25588
SUBJECT: LIGO/Virgo S190814bv: AT2019odc and AT2019omt 10.4m GTC spectroscopy
DATE:    19/08/31 13:21:18 GMT
FROM:    Alberto J. Castro-Tirado at IAA-CSIC  <ajct@iaa.es>

Y.-D. Hu  and A. J. Castro-Tirado (IAA-CSIC), A. F. Valeev and V. V.  Sokolov
(SAO-RAS), E. Fernandez-Garcia (IAA-CSIC), I. Carrasco and A. Castellon (UMA),
D. L. Tucker (Fermilab), M. Soares-Santos (Brandeis U), D. Garcia Alvarez
(GRANTECAN, IAC, ULL) and M. Rivero  (GRANTECAN), on behalf of a larger
collaboration, report:

Following the detection of desgw-190814r/AT2019odc and desgw-190814v/AT2019omt
(Soarez-Santos et al. GCNC 25486) within the error area of the GW event S190814bv
(LVC, GCNC 25324), we obtained imaging and optical spectra covering the range
5100-10000 A with the 10.4m GTC telescope equipped with OSIRIS in La Palma
(Spain) starting on Aug 30, 04:00 UT.

AT2019odc position lies in the bar of it host SBb galaxy, 0.7 arcsec away from
its center. On the stacked image with an exposure time of 2x15 s we could not
detect the transient itself. From the emission lines of the host galaxy, a
redshift z = 0.0540 +/- 0.0005 is measured, inside the expected LVC redshift
range. The slit also covered the transient expected position, but no broad lines
were detected.

AT2019omt is detected with r = 22.54 +/- 0.09 at Aug 30.  Cross-correlating the
spectrum (broad lines) with supernova template spectra in SNID (Blondin & Tonry,
2007), we find a good match to the spectra of SNIIL at several weeks post maximum
at a redshift of 0.1564 +/- 0.0005, based on the narrow emission lines from the
galaxy). Therefore we consider AT2019omt to be unrelated to the GW event S190814bv.

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