NICER observation list: Target ID 365801

Fast radio bursts (FRBs) are millisecond-duration pulses of radio emission that originate from an unidentified population of extragalactic sources. Thus far, 11 FRB sources have been found to produce repeat bursts. We propose to carry out a high-time resolution search for X-ray bursts from localized repeating FRB sources in the soft X-ray band using NICER. As of September 2019, FRB 121102 has entered an active state where multiple radio bursts have been detected. We propose for 50 ks of NICER observations of FRB 121102, coordinated with radio observations with the Deep Space Network 70 m telescopes as part of an on-going FRB monitoring program. We also request an additional 50 ks of NICER observing time for ToO joint radio/X-ray follow-up observations of other active repeating FRBs.