  Several recent measurements have been made of the angular correlation
function $w(\theta,m)$ of faint galaxies in deep surveys (e.g., Hubble Deep
Field, HDF). Are the measured correlations indicative of gravitational growth
of primordial perturbations or of the relationship between galaxies and (dark
matter dominated) galaxy haloes? A first step in answering this question is to
determine the typical spatial separations of galaxies whose spatial
correlations, $\xi(r,z),$ contribute most to w.
  The median spatial separation of galaxy pairs contributing to a fraction $p$
of $w$ for a galaxy survey is denoted by r_{eff} and compared with the
perpendicular distance, $r_\perp,$ at the median redshift, z_{median}, of the
galaxies. Over a wide range in $\xi$ growth rates $\epsilon$ and in
$z_{median}, \r_eff(50%) \ltsim r_\perp$ and $\r_eff(90%) \sim 4 r_\perp.$
  Values of r_eff for typical redshift distributions indicate that many $w$
measurements correspond to spatial correlations at comoving length scales well
below 1 h^-1 Mpc. For $\Omega_0=1$ and $\lambda_0=0$, the correlation signal at
4\arcsec predominant in the Villumsen et al. (1996) estimates of $w$ for faint
HDF galaxies corresponds to r_eff(50%)(HDF) \approx 40 h^-1 kpc; other
cosmologies and angles up to 10\arcsec can increase this to r_eff(50%)(HDF)
$\ltsim 200 h^-1 kpc. The proper separations are (1+z) times smaller.
  These scales are small: the faint galaxy $w$ measurements are at scales where
halo and/or galaxy existence, let alone interactions, may modify the spatial
correlation function. These measurements could maybe be used to probe the
radial extent of haloes at high redshift.
