A gas discharge lamp has a gas discharge vessel filled with a gas filling suitable for a gas discharge which emits VUV radiation, with a phosphor coating containing a downconversion phosphor. The downconversion phosphor has, in a host lattice, a pair of activators of a first lanthanoid ion and a second lanthanoid ion; a sensitizer selected from the group formed by the thallium(I) ion, lead(II) ion and bismuth(III) ion; and samarium(II) ion co-activator.