NICER observation list: Target ID 770801

We aim to trace the X-ray polarization properties across different accretion states of a black-hole X-ray binary in a single outburst. The best candidate to accomplish this goal is a newly discovered transient Swift J1727.8-1613, which is currently one of the brightest X-ray sources in the sky. IXPE has already observed it at the beginning of its outburst and detected a high average 2-8keV polarization fraction of 4% during the hard state. The source is poised to imminently undergo a spectral transition to the soft state. With this proposal, we aim to catch this source in the soft state and in the return transition to the low/hard state, which will allow us to study changes in the polarization properties and reveal how different X-ray emission regions evolve during the accretion states.