Prediction and Verification of Parker Solar Probe Solar Wind Sources at 13.3 R-circle dot

Drawing connections between heliospheric spacecraft and solar wind sources is a vital step in understanding the evolution of the solar corona into the solar wind and contextualizing in situ timeseries. Furthermore, making advanced predictions of this linkage for ongoing heliospheric missions, such as Parker Solar Probe (Parker), is necessary for achieving useful coordinated remote observations and maximizing scientific return. The general procedure for estimating such connectivity is straightforward (i.e., magnetic field line tracing in a coronal model) but validating the resulting estimates is difficult due to the lack of an independent ground truth and limited model constraints. In its most recent orbits, Parker has reached perihelia of 13.3R(circle dot) and moreover travels extremely fast prograde relative to the solar surface, covering over 120 degrees longitude in 3 days. Here we present footpoint predictions and subsequent validation efforts for Parker Encounter 10, the first of the 13.3R(circle dot) orbits, which occurred in November 2021. We show that the longitudinal dependence of in situ plasma data from these novel orbits provides a powerful method of footpoint validation. With reference to other encounters, we also illustrate that the conditions under which source mapping is most accurate for near-ecliptic spacecraft (such as Parker) occur when solar activity is low, but also require that the heliospheric current sheet is strongly warped by mid-latitude or equatorial coronal holes. Lastly, we comment on the large-scale coronal structure implied by the Encounter 10 mapping, highlighting an empirical equatorial cut of the Alfven surface consisting of localized protrusions above unipolar magnetic separatrices. Plain Language Summary Parker Solar Probe (Parker) is a NASA heliospheric mission which travels closer to the Sun than any previous human-made object, but also is the first to fly faster than the Sun rotates and so skims over its surface in a new way. To get the most out of Parker's science and to tie its measurements of the solar wind back to the physics happening at the Sun, we need to estimate the solar origin of the plasma which later arrives at Parker. This paper describes how we predict these locations in advance of seeing the Parker data as well as how we check how well we did after the fact. We show how Parker's extremely fast motion across the Sun in recent orbits leads to new and powerful ways to verify our estimates. We show the conditions which make our predictions the most accurate is when there is low solar activity, but plenty of "equatorial coronal holes": dark regions seen near the Sun's equator where the Sun's plasma is able to escape into space. Lastly, we show how the connectivity exercise combined with the novel Parker orbital motion allows us to "measure" a large portion of the Sun's atmosphere and relate these measurements to how the magnetic field lines of the Sun are arranged closer to the solar surface.