We constrain the distribution of merging compact binaries across the
celestial sphere using the GWTC-3 catalog from the LIGO-Virgo-KAGRA
Collaborations' (LVK) third observing run. With 63 confident detections from
O3, we constrain the relative variability (standard deviation) of the rate
density across the sky to be $\lesssim 16\mathrm{\%}$ at 90\% confidence assuming the
logarithm of the rate density is described by a Gaussian random field with
correlation length $\ge {10}^{\circ}$ . This tightens to $\lesssim 3.5\mathrm{\%}$ when the
correlation length is $\ge {20}^{\circ}$ . While the new O3 data provides the
tightest constraints on anisotropies available to-date, we do not find
overwhelming evidence in favor of isotropy, either. A simple counting
experiment favors an isotropic distribution by a factor of
${\mathcal{B}}_{\mathrm{ani}}^{\mathrm{iso}}=3.7$ , which is nonetheless an
improvement of more than a factor of two compared to analogous analyses based
on only the first and second observing runs of the LVK.