Color image of the Cosmic Horseshoe obtained through a combination of the F475W, F606W, and F814W filter images from the HST WFC3. The size of this image is 20″ × 20″. We can see the ≈300° wide blue Einstein ring of the Cosmic Horseshoe. In addition, the Cosmic Horseshoe observation includes a radial arc that is indicated with a green solid box. This is shown in detail in the bottom panel, in color (left) and from the F475W filter (right). We associate this radial arc to its counterimage, indicated in the main figure with a dashed green box and located around 8″ on the east side of the lens galaxy G. Both the radial arc and its counterimage correspond to a source at redshift z_s, r = 1.961 (see Sect. 2.2). The three star-like objects in the field of view, which we include in our light model, are circled in yellow. The figures are oriented such that north is up and east is left.