It's a Bird, it's a Plane, it's Radio Frequency Interference: Signalhound Characterizing Observatory Unwanted Transmissions*

Since its discovery by Penzias and Wilson in 1964, the Cosmic Microwave Background (CMB) has provided key insights to the structure, contents, and evolution of the Universe. In the current era of precision cosmology, long-term broadband observations of the CMB are increasingly susceptible to radio frequency interference (RFI) from a variety of terrestrial and extraterrestrial sources. As the global communication landscape continues to evolve, the characterization and mitigation of these unwanted signals is necessary for current and next generation CMB observation. Signalhound Characterizing Observatory Unwanted Transmissions (SCOUT) is a passive RFI monitor stationed at the Cerro Toco plateau in northern Chile, near a number of CMB observatories. In this work, I will discuss the motivation for continuous RFI monitoring, SCOUT’s development and deployment, and current efforts to support continued characterization of CMB observation sites.