Vol. 585
In section 1. Letters

Discovery of an exceptionally bright giant arc at z=2.369, gravitationally lensed by the Planck cluster PSZ1 G311.65-18.48

Strong gravitational lensing by intervening massive galaxy clusters has emerged as a powerful probe of high redshift galaxy populations, by providing a very powerful zoom on randomly picked examples. During a systematic follow up of the Planck sample of Sunyaev-Zeldovich cluster candidates, Dahle et al. identified an exceptionally bright giant arc, a full orrder of magnitude brighter than any previously known arc at similar redshifts. The arc is a vigorously star-forming galaxy at z=2.4 and will undoubtedly provide detailed insight into star formation and interstellar medium properties at a time when the universe was one quarter of its current age.