SIMBAD references

We discuss H-band (1.65 µm) near-infrared photometry of the central 9 h^–2 Mpc² of Abell 1644 (A1644) to a limiting M_H_~M*_H+3 (throughout this paper H₀=100 h km.s^–1 Mpc^–1). There are 861 galaxies in the photometric survey region. We also measured radial velocities of 155 galaxies; 141 of these are cluster members within 2.44 h^–1 Mpc of the cluster center. The completeness limit of the spectroscopic survey is H∼13 (M_H∼M^*_H). The cluster velocity dispersion of σ∼1000 km.s^–1 remains constant out to the limiting radius. We find no evidence for substructure in the cluster. The cluster mass within R=2.4 h^–1 Mpc is 7.6±1.3x10¹⁴ h^ -1^ M_☉. We compute the cluster luminosity function; the Schechter parameters α=-1.14±0.08 and M^*_H=-24.3±0.2 (with h=0.5) agree well with other H-band luminosity functions. From the virial theorem and the caustic method we compute one of the first mass-to-light ratios at H; the result is M/L_H=82-127 h M_☉/L_☉ within 1.5 h^–1 Mpc. This ratio corresponds to 374-579 h M_☉/L_☉ at R. The agreement of our IR measurement with previous M/L determinations indicates that at low redshift dust and young stellar populations may produce only negligible systematic errors in optical mass-to-light ratios.