Early warning detection of gravitational waves from binary neutron stars and neutron star-black hole coalescences

GW170817 was the first gravitational-wave event that was also observed in electromagnetic. However, it’s optical counterpart was not detected for 10 hours after merger since the sky-localization was below horizon for most of the observing telescopes. Therefore, we are left with open questions regarding the electromagnetic emission in every wavelength except gamma rays for the first ten hours. Our goal is to provide alerts for binary neutron stars and neutron star-black hole coalescences 10 s to a minute before merger, with a rough sky location so that the electromagnetic facilities can start the process of setting up their observations in advance of the merger making it possible to capture the earliest possible light with narrow field instruments. We present the results from a mock data study and show the expected rates and sky localizations of such events as a function of time before coalescence. We also present these results in particular from a case study of GW170817.