KIPAC Seminar: Measuring the Global 21-cm Signal from a Canyon and the Moon

Abstract: The redshifted 21-cm line of neutral hydrogen is one of the most promising probes of Cosmic Dawn, when the first stars, galaxies, and black holes formed. The sky-averaged (global) 21-cm signal can be measured with a single antenna and directly traces the thermal and ionization history of the intergalactic medium. The primary challenge is foreground emission four to five orders of magnitude brighter than the signal, which couples to instrumental systematics and can hide or mimic the cosmological signal.In this talk I present the Electromagnetically Isolated Global Signal Estimation Platform (EIGSEP), which targets the global signal from Cosmic Dawn and the Epoch of Reionization. EIGSEP uses an antenna suspended 100 m above the ground in a canyon to minimize terrain coupling, which could otherwise produce problematic spectral structure. A rotating antenna platform enables in-situ beam mapping and independent weightings of the beam pattern on the sky. I will describe the EIGSEP instrument as built and deployed, including results from the 2026 field campaign. I will close by discussing the LuSEE-Night experiment, which is scheduled to launch in 2027 and will serve as a pathfinder for 21-cm measurements from the lunar far side.