2001AJ....122...55W

We report the serendipitous discovery of a cluster of galaxies at z=0.369. Thirty-eight candidate members were identified based on rough broadband photometric redshifts, and three members were confirmed spectroscopically. The brightest cluster galaxy (BCG) is exceptionally blue, with B-V=0.12 and V-I=1.02. The surface-brightness profile of the BCG follows an r^1/4 law profile out to 3" in all three bands. The effective radius is significantly smaller in bluer bandpasses, resulting in a blue core and a color gradient opposite to the metallicity-induced color gradient observed in typical elliptical galaxies. Beyond 3", an extended envelope of emission in excess of the r^1/4 law profile is observed, the position angle of which coincides with the major axis of the galaxy cluster. The spectrum of the BCG contains strong Balmer absorption, a minimal 4000 Å break, and a broad Mg II emission line, suggesting that the galaxy has undergone recent star formation and may harbor a central active galactic nucleus. The presence of numerous nearby bright stars makes this cluster an interesting target for next-generation adaptive optics using natural guide stars.