Underwater acoustic source localization is important during disaster-rescue missions ranging from rescuing survivors to recovering acoustically-tagged artifacts such as black box. Designing acoustic localization capabilities reliably and efficiently is challenging. Underwater acoustic localization module (UALM) utilizing multiple signal classification (MUSIC) is implemented on an autonomous underwater vehicle (AUV). A state-machine based application program interface (API) is utilized on the AUV operating on robot operating system (ROS). An array of four pre-calibrated hydrophones is utilized for geometry-dependent MUSIC computation. A modular localization approach improved UALM's responsiveness.