Padova-Asiago Supernova Group

Optical follow-up of gravitational wave events during the second advanced LIGO/VIRGO observing run with the DLT40 Survey
Yang, S. et al. 2019, ApJ in press (ArXIV 1901.08474)
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We describe the gravitational wave (GW) follow-up strategy and subsequent results of the Distance Less Than 40 Mpc survey (DLT40) during the second science run (O2) of the Laser Interferometer Gravitational-wave Observatory and Virgo collaboration (LVC). Depending on the information provided in the GW alert together with the localization map sent by the LVC, DLT40 would respond promptly to image the corresponding galaxies selected by our ranking algorithm in order to search for possible electromagnetic (EM) counterparts in real time. During the LVC O2 run, DLT40 followed ten GW triggers, observing between ∼20-100 galaxies within the GW localization area of each event. From this campaign, we identified two real transient sources within the GW localizations with an appropriate on-source time – one was an unrelated type Ia supernova (SN 2017cbv), and the other was the optical kilonova, AT 2017fgo/SSS17a/DLT17ck, associated with the binary neutron star coalescence GW170817 (a.k.a gamma-ray burst GRB170817A). We conclude with a discussion of the DLT40 survey’s plans for the upcoming LVC O3 run, which include expanding our galaxy search fields out to D≈65 Mpc to match the LVC’s planned three-detector sensitivity for binary neutron star mergers. 188