J1721+8842: The first Einstein zigzag lens F. Dux, M. Millon, C. Lemon, T. Schmidt, F. Courbin, A. J. Shajib, T. Treu, S. Birrer, K. C. Wong, A. Agnello et al. (9 more) A&A, 694 (2025) A300 Published online: 20 February 2025 DOI: 10.1051/0004-6361/202452970