Harbingers of Exotic Transients: The EM Follow-up of Gravitational-wave Transients & EMGW astronomy

The simultaneous detection of gravitational waves (GWs) from the binary neutron star (BNS) merger, GW170817, gamma-rays, and its electromagnetic (EM) counterpart, the kilonova AT 2017gfo, marked the dawn of multi-messenger EMGW astronomy. The scientific impact of such joint observations is extremely rich. But it remains the only success story of EMGW astronomy, even after the LIGO/Virgo third observing run which reported 56 GW discoveries publicly. This shows that while we may have reached an era of routine GW astronomy, the same for EMGW astronomy still awaits us. The first step is to develop a low-latency alerting system and data-products that aid the follow-up. Here, I will talk about the efforts and results from the LIGO/Virgo third observing run. I will also talk about the determination of detection efficiency for time-domain telescope, focusing on iPTF, and how it ties into estimating transient rates.