NICER observation list: Target ID 762402

eROSITA has the capability to identify exceptional AGN with periodic X-ray flux signals. These objects are potential supermassive black hole binaries (SMBHB). We request six monitoring campaigns for a total exposure of 360ks for the brightest eROSITA-selected candidate periodic AGN. Each campaign consists of six individual pointings of 10 ks each, spaced roughly four weeks apart. The campaigns are needed to track the flux modulation, discard stochastic variability, and determine the details of higher cadence NICER follow-up observations to confirm the periodic nature. The most convincing case will be observed with XMM-Newton to find a double-peaked Fe Ka line coming from the individual accretion disks of the SMBHBs. This project could discover the closest distance SMBHB up to date.