NICER observation list: Target ID 364901

We propose to advance our understanding of stellar wind dynamics by performing first ever systematic monitoring of HMXB OAO 1657 415. With a NICER observation of 2 ks every alternate day spread uniformly at different orbital phases for 20 days (2 orbits) we will measure NH & equivalent width of its prominent iron Kalpha line at these orbital phases, thereby mapping clump distribution and characterizing them. By stacking these individual 2 ks spectra, we will also generate the first orbital phase-resolved spectra for the source and look for possible massive structures throughout its orbit. Finally, during this monitoring campaign, we will also investigate detailed changes in the morphology of pulse-profiles in each observation, all possible thanks to large effective area of NICER.