M. Nicholl, P. Short (Edinburgh), J. Anderson (ESO), T.-W. Chen (MPE), C. Inserra (Cardiff), O. Yaron (Weizmann), D. R. Young, S. J. Smartt (QUB), C. Angus, M. Pursiainen, P. Wiseman (Southampton), S. Taubenberger (MPA), M. Gromadzki (Warsaw) on behalf of the ePESSTO+ collaboration
We report observations of two possible counterparts to the LIGO/Virgo gravitational wave trigger S190425z (GCN 24168), under the the advanced Public ESO Spectroscopic Survey for Transient Objects (ePESSTO+; see Smartt et al. 2015, A&A, 579, 40 http://www.pessto.org). The observations were performed on the ESO New Technology Telescope at La Silla with the EFOSC2 instrument.
ZTF19aarzaod/AT2019dzw was announced by Kasliwal et al. (GCN 24191) as a promising candidate from a ZTF search of the field. Follow-up spectroscopy by Buckley et al. (GCN 24205), Izzo et al. (GCN 24208) and Wiersema et al. (GCN 24209) indicated the transient is a young Type II supernova. Our NTT spectrum shows a broad feature consistent with H-alpha at the redshift of the host galaxy (z=0.028).
ATLAS19hwn/AT2019ebm was announced by McBrien et al. (GCN 24197) as a marginal candidate identified during targeted imaging of the localisation region by ATLAS. Follow up observations by Perley et al. (GCN 24202) did not recover the reported source to a limit of r>22.0 mag. We obtained deep imaging to look for a rapidly fading transient. A 5x200s observation in r band shows no source at this position, with preliminary analysis indicating a limit of r>23 mag.