AERA: the Auger Engineering Radio Array

The first part of the Auger Engineering Radio Array, presentl y consisting of 21 radio-detection stations, has been installed in the surface detector array of the Pierre Au ger Observatory and in close proximity to the fluorescence detectors Coihueco and HEAT. In the coming years, the number of detection stations will grow to 160 units covering an area of almost 20 square kilometers. AERA is sensitive to radio emission from air showers with an energy threshold of 10 17 eV and is being used to study in detail the mechanisms responsible for radio emission in the VHF band. The design of AERA is based on results obtained from prototype setups, with which we investigated triggering methods and different hardware concepts. We present the first data from AERA, inclu ding AERA's first hybrid radio / particle detector events.