2026ApJ...998..146S

While the temporal variations of the spectropolarimetric nature of pulsars remain unexplored, this investigation offers significant potential for uncovering key insights into pulsar emission mechanisms, magnetic field geometry, and propagation effects within the magnetosphere. We developed a package for investigating time-varying spectral behavior for full Stokes parameters and demonstrate it on a millisecond pulsar (MSP), J2144-5237, in a binary system (orbital period ∼10 days) using the Parkes Ultra-Wideband Low receiver. In this study we report rotation measure variation with orbital phase. We find that the temporal variations in the spectra of Stokes I, Q, and V are generally correlated throughout the orbit, while Stokes U exhibits intervals of both correlation and anticorrelation with Stokes I, depending on the orbital phase. We also provide a Poincaré sphere representation of the polarization properties of J2144-5237, demonstrating a systematic temporal change of Poincaré sphere location for the main component with orbital phase. To our knowledge, this is the first investigation of the time-varying properties of the spectropolarimetric nature of any pulsars or MSPs. Extending this study to probe the spectrotemporal nature of full Stokes data on a larger sample of MSPs or pulsars has the potential to provide vital information on emission mechanisms inside the magnetosphere, interstellar propagation effects, and binary interactions.