  We present a catalog of 799 clusters of galaxies in the redshift range z_est
= 0.05 - 0.3 selected from ~400 deg^2 of early SDSS commissioning data along
the celestial equator. The catalog is based on merging two independent
selection methods -- a color-magnitude red-sequence maxBCG technique (B), and a
Hybrid Matched-Filter method (H). The BH catalog includes clusters with
richness \Lambda >= 40 (Matched-Filter) and N_gal >= 13 (maxBCG), corresponding
to typical velocity dispersion of \sigma_v >~ 400 km s^{-1} and mass (within
0.6 h^{-1) Mpc radius) >~ 5*10^{13} h^{-1} M_sun. This threshold is below Abell
richness class 0 clusters. The average space density of these clusters is
2*10^{-5} h^3 Mpc^{-3}. All NORAS X-ray clusters and 53 of the 58 Abell
clusters in the survey region are detected in the catalog; the 5 additional
Abell clusters are detected below the BH catalog cuts. The cluster richness
function is determined and found to exhibit a steeply decreasing cluster
abundance with increasing richness. We derive observational scaling relations
between cluster richness and observed cluster luminosity and cluster velocity
dispersion; these scaling relations provide important physical calibrations for
the clusters. The catalog can be used for studies of individual clusters, for
comparisons with other sources such as X-ray clusters and AGNs, and, with
proper correction for the relevant selection functions, also for statistical
analyses of clusters.
