IMAP-Ultra Observations of Heliospheric Energetic Neutral Atoms

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Abstract
NASA’s Interstellar Mapping and Acceleration Probe (IMAP) mission is providing comprehensive observations of both the in situ magnetic field and charged particle environment as well as remotely exploring energetic neutral atoms (ENAs), dust particles, and ultraviolet photons that originate from the outer heliosphere and beyond. Collectively, these measurements will advance our understanding of particle acceleration throughout the solar system and how the solar wind and interstellar medium interacts with the boundary of our heliosphere. Here, we focus on heliospheric observations from the IMAP-Ultra (Ultra) instrument, which is one of three ENA imagers on IMAP. Ultra measures ~3 – 100 keV neutral atoms over its large ~96° × 120° field of view (FoV), achieving angular resolutions ≤ 6° above 10 keV for H. Since IMAP’s launch on September 24, 2025, both Ultra sensors have been fully commissioned and are collecting new and exciting observations of the heliosphere. In this presentation, we highlight the global heliospheric configuration of > 3.7 keV H ENAs with detailed investigations into its spectral variations, evolving heliotail structure as a function of energy, and high angular resolution structures (up to 2° for energies > 30 keV).