Lensing model of BRI 0952-0115. Left panel: the lens galaxy (at z = 0.632) is located at the center of the image. The black contours represent the BRI 0952-0115 position required to match optical observations. The mass distribution of the source is described in terms of a circular Gaussian function with FWHM ~ 0.07′′. The red curves around the position of the lens denote the tangential caustic, while the blue ellipse shows the radial caustic. Right panel: resulting image configuration and critical lines in the lens plane. The source is strongly lensed by the foreground galaxy and mapped onto a set of double images: the black contours represent the lensed images of BRI 0952-0115. Red crosses represent the relative position of A and B from the lensing galaxy location (filled red square), as measured by Lehár et al. (2000) in the optical images. Contour levels are shown at 20%, 50%, and 80% of the peak.