SIMBAD references

We present magnitudes and redshifts of galaxies in the cluster of galaxies CL 0017-20 and in the double cluster CL 0500-24. Luminosity functions and velocity distributions have been derived. CL 0017-20 possesses a virial mass of 2.9x10¹⁴M_☉ and a V-band luminosity of 2.3±0.5x10¹²L_☉ (M/L_V=127), much of it in a very compact core of size 113kpc. Our new velocities and photometry of CL 0500-24 confirm its double nature. Our group algorithm clearly detects two subconcentrations with masses 1.9 and 2.2x10¹⁴M_☉. Its total V-band luminosity amounts to 2.7±0.8x10¹²L_☉ (M/L_V of 157). Since the crossing and collapse times in both clusters are smaller than the age of the Universe, they appear bound and virialized. It is surprising that although M/L is small in these clusters, giant arcs have been detected in both.