Agnello, A.Lin, H.Buckley-Geer, L.Treu, T.Bonvin, V.Courbin, F.Lemon, C.Morishita, T.Amara, A.Auger, M. W.Birrer, S.Chan, J.Collett, T.More, A.Fassnacht, C. D.Frieman, J.Marshall, P. J.Mcmahon, R. G.Meylan, G.Suyu, S. H.Castander, F.Finley, D.Howell, A.Kochanek, C.Makler, M.Martini, P.Morgan, N.Nord, B.Ostrovski, F.Schechter, P.Tucker, D.Wechsler, R.Abbott, T. M. C.Abdalla, F. B.Allam, S.Benoit-Levy, A.Bertin, E.Brooks, D.Burke, D. L.Rosell, A. CarneroKind, M. CarrascoCarretero, J.Crocce, M.Cunha, C. E.D'Andrea, C. B.Da Costa, L. N.Desai, S.Dietrich, J. P.Eifler, T. F.Flaugher, B.Fosalba, P.Garcia-Bellido, J.Gaztanaga, E.Gill, M. S.Goldstein, D. A.Gruen, D.Gruendl, R. A.Gschwend, J.Gutierrez, G.Honscheid, K.James, D. J.Kuehn, K.Kuropatkin, N.Li, T. S.Lima, M.Maia, M. A. G.March, M.Marshall, J. L.Melchior, P.Menanteau, F.Miquel, R.Ogando, R. L. C.Plazas, A. A.Romer, A. K.Sanchez, E.Schindler, R.Schubnell, M.Sevilla-Noarbe, I.Smith, M.Smith, R. C.Sobreira, F.Suchyta, E.Swanson, M. E. C.Tarle, G.Thomas, D.Walker, A. R.2018-01-152018-01-152018-01-15201710.1093/mnras/stx2242https://infoscience.epfl.ch/handle/20.500.14299/144109WOS:000415652500022We present detailed modelling of the recently discovered, quadruply lensed quasar J0408-5354, with the aim of interpreting its remarkable configuration: besides three quasar images (A, B, D) around the main deflector (G1), a fourth image (C) is significantly reddened and dimmed by a perturber (G2) which is not detected in the Dark Energy Survey imaging data. From lens models incorporating (dust-corrected) flux ratios, we find a perturber Einstein radius 0.04 arcsec less than or similar to R-E,R- G2 less than or similar to 0.2 arcsec and enclosed mass M-p(R-E,R- G2) less than or similar to 1.0 x 10(10) M-circle dot. The main deflector has stellar mass log(10)(M-star/M-circle dot) = 11.49(-0.32)(+0.46), a projected mass M-p(R-E,R- G1) approximate to 6 x 10(11) M-circle dot within its Einstein radius R-E,R- G1 = (1.85 +/- 0.15) arcsec and predicted velocity dispersion 267-280 km s(-1). Follow-up images from a companion monitoring campaign show additional components, including a candidate second source at a redshift between the quasar and G1. Models with free perturbers, and dust-corrected and delay-corrected flux ratios, are also explored. The predicted time-delays (Delta t(AB) = (135.0 +/- 12.6) d, Delta t(BD) = (21.0 +/- 3.5) d) roughly agree with those measured, but better imaging is required for proper modelling and comparison. We also discuss some lessons learnt from J0408-5354 on lensed quasar finding strategies, due to its chromaticity and morphology.gravitational lensing: strongmethods: statisticaltechniques: image processingcataloguestext::journal::journal article::research article