Auger at the Telescope Array: Recent Progress Toward a Direct Cross-Calibration of Surface-Detector Stations

Since 2007 the Telescope Array Project (TA) and the Pierre Auger Observatory (Auger) have collected extensive data sets spanning several orders of magnitude in energy of the cosmic-ray spectrum. In both experiments the bulk of data is generated from the surface-detector (SD) array, which is energetically calibrated with fluorescence detectors using a hybrid approach. However, each experiment has implemented a different SD station design, resulting in different sensitivities of extensive air-shower channels. Understanding these differences and any potential unforeseen systematic errors is essential for future joint analyses. In this paper we present an update on the progress of an in-situ cross-calibration program. We focus on recent hardware installations which enable the read out of co-located Auger and TA SD stations at the TA central laser facility (CLF). We also present a preliminary analysis of event signals observed at the CLF.