Auger at the Telescope Array: toward a direct cross-calibration of surface-detector stations

Since 2007 the Telescope Array Project (TA) and Pierre Auger Observatory (Auger) have collected extensive data sets spanning several orders of magnitude of the cosmic-ray spectrum. In both experiments the majority of data is generated from the surface-detector (SD) array as a result of its very high duty cycle. These data are then calibrated for energy with fluorescence detectors using a hybrid approach. The TA and Auger experiments use different SD station designs, giving them different sensitivities to extensive air-shower components. We seek to understand and cross-validate these complementary detectors on a hardware level. In this paper we present an update on the progress of this in-situ cross-calibration program. Presently two Auger water-Cherenkov detectors and two TA scintillator stations are co-located at the TA central laser facility (CLF). We review the hardware enabling the readout of these detectors for high-energy events. Additionally, we show expanded calibration data sets of minimum-ionizing particle (MIP) versus vertical-equivalent muon (VEM) responses, along with preliminary results for the Auger doublet. A sample event reconstruction displaying observed Auger and TA signals is also presented.