Auger@TA: Instrumentation, performance, and preliminary results of an in-situ cross-calibration

The two largest ultra-high energy cosmic ray (UHECR) observatories, the Pierre Auger Observatory and the Telescope Array (TA), operate at similar latitudes in the Southern and Northern hemispheres, respectively. When the UHECR spectra measured by both observatories are compared, discrepancies are observed, particularly at high energies. This discrepancy may be due to differences in their Surface Detector (SD) types, reconstruction methods, or astrophysics. To directly investigate the cause of this disagreement in-situ, the Auger@TA project was conceived, consisting of a hexagonal array of eight Auger-type SD stations installed within TA in Utah. This stand-alone array is now operational, recording air showers at a rate of approximately five events per week. Now that data-taking is underway, the project has transitioned to the analysis phase. Auger@TA reconstructions leverage event core positions provided by TA to improve the reconstruction of events triggered independently in the Auger@TA array. This dual-observatory method allows for precise event-by-event comparisons of event energies and rates between the two experiments. In parallel, detailed simulations of the array are being carried out to validate the reconstructions and quantify systematic uncertainties. This contribution will detail the instrumentation of Auger@TA, its performance, and preliminary results from the analysis of events measured by the array thus far.