The Helix Nebula (NGC 7293) is one of the closest and brightest planetary nebulae, and therefore a benchmark for resolving how the late-stage ejecta of stars couple to their surroundings. Using the Gaia EDR3/DR3 astrometric solution for the central star (WD 2226-210), we adopt a distance of d = 198.6 (+1.6/−1.8) pc (ref. 10). Imaging of the Helix
United Nations Treaty on Principles Governing the Activities of States in the Exploration and Use of Outer Space, Including the Moon and Other Celestial Bodies. United Nations General Assembly Resolution 2222 (XXI); entered into force on October 10, 1967. https://www.unoosa.org/oosa/en/ourwork/spacelaw/treaties/outerspacetreaty.html (1967). Carpenter, J.M. Pulsed spallation neutron sources for slow neutron scattering. Core. Instrument. Methods 14591-113