NICER observation list: Target ID 360402

Ultra-compact X-ray binaries (UCXBs) are a subclass of low-mass X-ray binaries that contain a degenerate stellar companion in a short orbit (< 80 mins). The accretion disk in these systems differ in chemical composition from typical LMXBs due to a lack of hydrogen and overabundance of higher Z elements. These systems exhibit multiple emission lines in their reflection spectrum from O and Fe. These multiple emission features offer the opportunity to learn more about the properties of the compact object and accretion disks in these systems. We request 10 ks NICER observations and joint 30 ks NuSTAR observations of two UCXBs to reveal the entire reflection spectrum from low-E oxygen features to the Compton hump at higher energy to enhance our understanding of accretion in these systems.