THE ENVELOPE OF THE RED GALAXIES DISTRIBUTION IN A Z=0.75 CLUSTER FIELD

We report the observation of a group of 16 red (V - I > 2) galaxies, i n the magnitude range 22 less than or equal to V less than or equal to 25.5, within a projected distance of 30 '' (similar to 0.2 h(-1) Mpc for h = H-o/75 km s(-1) Mpc(-1)) of the ultra-steep spectrum radio sou rce 1443-198 at z = 0.753. The colours of the galaxies range from the cut-off at V - I = 2.0 to V - I = 3.3. Eight galaxies are redder than V - I = 2.3 and three are redder than V - I = 3.0. Some objects with I approximate to 23 are undetected at the magnitude limit of V = 25.5. This confirms previous results on the presence of a very red envelope in some distant clusters and suggests that a fraction of cluster ellip ticals are already old at z approximate to 0.75. The radio galaxy has colours and a 4000 Angstrom break amplitude typical of evolving E/S0 g alaxies, and shows signs of interaction with other objects in its imme diate vicinity.