NICER observation list: Target ID 755102

Irradiation of a standard accretion disk by a compact X-ray source cannot explain the observed X-ray/UV lags in NGC 4151 despite UV/Optical lags which follow predictions, suggesting an extended X-ray corona or an additional reprocessor between the X-rays and the disk. However, the source is affected by highly variable obscuration which may distort size estimates of the soft X-ray corona using observed count rates. Our 4-month NICER campaign will deliver X-ray spectra with a daily cadence and sufficient S/N to obtain time-resolved measurements of the intrinsic X-ray fluxes in multiple bands, which will be tested for correlation with coordinated UV/Optical observations to map the X-ray corona and inner disk.