Wu, ZDong, SMérand, AKochanek, CSMróz, PShangguan, JChristie, GTan, TGBensby, TBland-Hawthorn, JBuder, SEisenhauer, FGould, APKos, JNatusch, TSharma, SUdalski, AWoillez, JBuckley, DAHThompson, IBEl Dayem, KABerdeu, ABerger, JPBourdarot, GBrandner, WDavies, RIDefrère, DDougados, CDrescher, AEckart, AFabricius, MFeuchtgruber, HFörster Schreiber, NMGarcia, PGenzel, RGillessen, SHeißel, GHönig, SHoulle, MKervella, PKreidberg, LLacour, SLai, OLaugier, RLe Bouquin, JBLeftley, JLopez, BLutz, DMang, FMillour, FMontargès, MNowacki, HNowak, MOtt, TPaumard, TPerraut, KPerrin, GPetrov, RPetrucci, POPourre, NRabien, SRibeiro, DCRobbe-Dubois, SSadun Bordoni, MSantos, DSauter, JScigliuto, JShimizu, TTStraubmeier, CSturm, ESubroweit, MSykes, CTacconi, LVincent, FWidmann, F2025-01-302025-01-302024-12-17Astrophysical Journal, ISSN: 0004-637X (Print); 1538-4357 (Online), American Astronomical Society, 977(2), 229-229. doi: 10.3847/1538-4357/ad90b90004-637X1538-4357http://hdl.handle.net/10292/18560We resolve the multiple images of the binary-lens microlensing event ASASSN-22av using the GRAVITY instrument of the Very Large Telescope Interferometer (VLTI). The light curves show weak binary-lens perturbations, complicating the analysis, but the joint modeling with the VLTI data breaks several degeneracies, arriving at a strongly favored solution. Thanks to precise measurements of the angular Einstein radius θ E = 0.724 ± 0.002 mas and microlens parallax, we determine that the lens system consists of two M dwarfs with masses of M 1 = 0.258 ± 0.008 M ⊙ and M 2 = 0.130 ± 0.007 M ⊙, a projected separation of r ⊥ = 6.83 ± 0.31 au, and a distance of D L = 2.29 ± 0.08 kpc. The successful VLTI observations of ASASSN-22av open up a new path for studying intermediate-separation (i.e., a few astronomical units) stellar-mass binaries, including those containing dark compact objects such as neutron stars and stellar-mass black holes.Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.http://creativecommons.org/licenses/by/4.0/5101 Astronomical Sciences51 Physical Sciences0201 Astronomical and Space Sciences0202 Atomic, Molecular, Nuclear, Particle and Plasma Physics0306 Physical Chemistry (incl. Structural)Astronomy & Astrophysics5101 Astronomical sciences5107 Particle and high energy physics5109 Space sciencesJournal ArticleOpenAccess10.3847/1538-4357/ad90b9