We present new optical data on the cluster AX J2019+1127 identified by the X-ray satellite ASCA at z \sim 1 ( 13 ) .
The data suggest the presence of a high-redshift cluster of galaxies responsible for the large separation triple quasar MG2016+112 .
Our deep photometry reveals an excess of z \sim 1 galaxy candidates , as already suspected by Benítez et al . ( ) benitez99 .
Our spectroscopic survey of 44 objects in the field shows an excess of 6 red galaxies securely identified at z \sim 1 , with a mean redshift of z = 1.005 \pm 0.002 .
We estimate a velocity dispersion of \sigma = 771 ^ { +430 } _ { -160 } km s ^ { -1 } based on these 6 galaxies and a V-band mass-to-light ratio of 215 ^ { +308 } _ { -77 } h _ { 50 } ( M / L _ { V } ) _ { \odot } .
Our observations thus confirm the existence of a massive structure acting as the lens , which explains the unusual configuration of the triple quasar .
Hence , there is no need to invoke the existence of a “ dark cluster ” to understand this lens system .