Searching electromagnetic counterpart of gravitational waves

During the second scientific run (O2) of LIGO/VIRGO collaboration (LVC), an epochal breakthrough occurred when the first binary neutron star (BNS) gravitational wave (GW) event was detected (GW170817) and associated to the weak short GRB170817A detected by the Fermi and Integral satellites. DLT40 was the second of the six groups which independently detected the associated optical kilonova, DLT17ck 11 hours after the GW channel. Multimessenger astronomy, the detection of an astrophysical source with more than one `messenger’ (photons, gravitational waves, neutrinos), has truly begun. In this paper, we report the DLT40 GW follow-up searching results in the LVC O2 season. Two transients have been discovered (DLT17u, DLT17ck) by DLT40 in the process of triggering the GW information and only one is identified as related to the GW event. The paper outlines the DLT40 galaxy prioritization strategy and the procedures developed to search for transient counterpart candidates.