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Abstract The current morphology of Earth’s time-averaged magnetic field can be approximated to a geocentric axial dipole (GAD), but whether such an approximation remains valid in deep time needs to be investigated. Studies have used paleomagnetic data to reconstruct the ancient field and generally support a GAD morphology since 2 Ga. Recently, the GAD model for mid-Proterozoic time has been challenged, and an alternative model was proposed wherein the mid-Proterozoic field was dominated by a normal-tesseral quadrupole (NTQ) with spherical harmonics of degree l = 2 and order m = 1. We performed forward modeling to quantitatively compare whether a GAD or an NTQ could provide a better fit to mid-Proterozoic paleomagnetic directions. To deal with the ambiguity in plate reconstruction, we first considered data only from Laurentia, and then we expanded the analysis to Baltica by reconstructing its position relative to Laurentia using the geologically based Northern Europe–North America (NENA) configuration. Finally, we included data from Siberia using two reconstruction models. Results showed that in three mid-Proterozoic intervals (1790–1740 Ma, 1485–1425 Ma, 1095–1080 Ma), a GAD morphology gives better, or equally good, fits compared to the NTQ morphology. In addition, a stable NTQ that persisted for hundreds of millions of years is disfavored from a geodynamic perspective. Overall, mid-Proterozoic paleomagnetic directions are more consistent with a dipolar field. We suggest that the GAD remains the most parsimonious model to describe the morphology of the mid-Proterozoic magnetic field. 

PFS (Prime Focus Spectrograph), a next generation facility instrument on the Subaru telescope, is now being tested on the telescope. The instrument is equipped with very wide (1.3 degrees in diameter) field of view on the Subaru's prime focus, high multiplexity by 2394 reconfigurable fibers, and wide waveband spectrograph that covers from 380nm to 1260nm simultaneously in one exposure. Currently engineering observations are ongoing with Prime Focus Instrument (PFI), Metrology Camera System (MCS), the first spectrpgraph module (SM1) with visible cameras and the first fiber cable providing optical link between PFI and SM1. Among the rest of the hardware, the second fiber cable has been already installed on the telescope and in the dome building since April 2022, and the two others were also delivered in June 2022. The integration and test of next SMs including near-infrared cameras are ongoing for timely deliveries. The progress in the software development is also worth noting. The instrument control software delivered with the subsystems is being well integrated with its system-level layer, the telescope system, observation planning software and associated databases. The data reduction pipelines are also rapidly progressing especially since sky spectra started being taken in early 2021 using Subaru Nigh Sky Spectrograph (SuNSS), and more recently using PFI during the engineering observations. In parallel to these instrumentation activities, the PFS science team in the collaboration is timely formulating a plan of large-sky survey observation to be proposed and conducted as a Subaru Strategic Program (SSP) from 2024. In this article, we report these recent progresses, ongoing developments and future perspectives of the PFS instrumentation.