A LARGE STRUCTURE OF GALAXIES AT A REDSHIFT Z = 0.985

During the course of a CFHT/MOS deep redshift survey of objects brighter than I(AB) = 22.5 in a 10' x 10' field chosen at alpha = 14h15m, delta = 52-degrees-44' we have spectroscopically identified a QSO with a redshift z = 0.9848, and 12 galaxies with [z] = 0.986 and a velocity dispersion among them of 955 km s-1. These objects are distributed throughout the region, within 4 h-50(-1) Mpc (q0 = 0) from the QSO, and with a marginal density enhancement near the QSO. Since we have measured redshifts for about one-third of the objects in the field, this structure could harbor an average of 30 galaxies with L > L*, within a projected area 50 h50(-2) Mpc-2. The galaxy density excess is estimated to be 5-10 times the local mean density, based on the redshift distribution of 150 galaxies with redshifts measured in this field and comparison with our other survey fields. This is, so far, the highest redshift for which a physical association of galaxies on such scales has been demonstrated from secure redshift measurements.