NICER observation list: Target ID 750201

Ultracompact white dwarf binaries are the most compact binary star systems known and can have orbital periods shorter than 5 minutes. Their evolution is influenced by the loss of angular momentum due to the emission of gravitational radiation, and they are highly anticipated targets for space-based gravitational wave detection. We propose to continue to monitor the soft X-ray pulsations from HM Cnc and V407 Vul, two ultracompact white dwarf binary systems. HM Cnc is the most compact binary star system presently known, and NICER monitoring has provided new insights into its binary evolution. Continued monitoring with NICER will enable detailed probes of binary evolution driven by gravitational radiation and direct impact accretion.