We use the Sloan Digital Sky Survey ( SDSS ) spectroscopic sample to constrain the projected radial distribution of satellites around isolated \sim L _ { \ast } galaxies .
We employ mock galaxy catalogs derived from high-resolution cosmological simulations to investigate the effects of interloper contamination and show that interlopers significantly bias the estimated slope of the projected radial distribution of satellites .
We also show that the distribution of interlopers around galaxies is expected to be non-uniform in velocity space because galaxies are clustered and reside in crowded environments .
Successful methods of interloper contamination correction should therefore take into account environments of the host galaxies .
Two such new methods are presented and the most reliable of them is used to correct for interloper contamination in analyses of the SDSS galaxy sample .
The best fit power-law slope of the interloper-corrected surface density distribution of satellites , \Sigma ( R ) \propto R ^ { \alpha } , in the volume-limited SDSS sample is \alpha \simeq - 1.7 \pm 0.1 , independent of the galaxy and satellite luminosities .
Comparison with \Lambda CDM simulations shows that the radial distribution of the SDSS satellites is more concentrated than that of subhalos around galaxy-sized halos , especially at R < 100 h ^ { -1 } kpc .
The predicted dark matter radial distribution is somewhat more concentrated than the profile of the SDSS satellites , but the difference is not statistically significant for our sample .