  The bimodal absorption system imaging campaign (BASIC) aims to characterize
the galaxy environments of a sample of 36 HI-selected partial Lyman limit
systems (pLLSs) and Lyman limit systems (LLSs) in 23 QSO fields at $z \lesssim
1$. These pLLSs/LLSs provide a unique sample of absorbers with unbiased and
well-constrained metallicities, allowing us to explore the origins of
metal-rich and low-metallicity circumgalactic medium (CGM) at $z<1$. Here we
present Keck/KCWI and VLT/MUSE observations of 11 of these QSO fields (19
pLLSs) that we combine with HST/ACS imaging to identify and characterize the
absorber-associated galaxies. We find 23 unique absorber-associated galaxies,
with an average of one associated galaxy per absorber. For seven absorbers, all
with $<10\%$ solar metallicities, we find no associated galaxies with $\log
M_\star \gtrsim 9.0$ within $\rho/R_{vir}$ and $|\Delta v|/v_{esc} \le$ 1.5
with respect to the absorber. We do not find any strong correlations between
the metallicities or HI column densities of the gas and most of the galaxy
properties, except for the stellar mass of the galaxies: the low-metallicity
([X/H] $\le -1.4$) systems have a probability of $0.39^{+0.16}_{-0.15}$ for
having a host galaxy with $\log M_\star \ge 9.0$ within $\rho/R_{vir} \le 1.5$,
while the higher metallicity absorbers have a probability of
$0.78^{+0.10}_{-0.13}$. This implies metal-enriched pLLSs/LLSs at $z<1$ are
typically associated with the CGM of galaxies with $\log M_\star > 9.0$,
whereas low-metallicity pLLSs/LLSs are found in more diverse locations, with
one population arising in the CGM of galaxies and another more broadly
distributed in overdense regions of the universe. Using absorbers not
associated with galaxies, we estimate the unweighted geometric mean metallicity
of the intergalactic medium to be [X/H] $\lesssim -2.1$ at $z<1$, which is
lower than previously estimated.
