Galaxy And Mass Assembly (GAMA): The galaxy stellar mass function to
  $z=0.1$ from the r-band selected equatorial regions
  We derive the low redshift galaxy stellar mass function (GSMF), inclusive of
dust corrections, for the equatorial Galaxy And Mass Assembly (GAMA) dataset
covering 180 deg$^2$. We construct the mass function using a density-corrected
maximum volume method, using masses corrected for the impact of optically thick
and thin dust. We explore the galactic bivariate brightness plane
($M_\star-\mu$), demonstrating that surface brightness effects do not
systematically bias our mass function measurement above 10$^{7.5}$ M$_{\odot}$.
The galaxy distribution in the $M-\mu$-plane appears well bounded, indicating
that no substantial population of massive but diffuse or highly compact
galaxies are systematically missed due to the GAMA selection criteria. The GSMF
is {fit with} a double Schechter function, with $\mathcal
M^\star=10^{10.78\pm0.01\pm0.20}M_\odot$,
$\phi^\star_1=(2.93\pm0.40)\times10^{-3}h_{70}^3$Mpc$^{-3}$,
$\alpha_1=-0.62\pm0.03\pm0.15$,
$\phi^\star_2=(0.63\pm0.10)\times10^{-3}h_{70}^3$Mpc$^{-3}$, and
$\alpha_2=-1.50\pm0.01\pm0.15$. We find the equivalent faint end slope as
previously estimated using the GAMA-I sample, although we find a higher value
of $\mathcal M^\star$. Using the full GAMA-II sample, we are able to fit the
mass function to masses as low as $10^{7.5}$ $M_\odot$, and assess limits to
$10^{6.5}$ $M_\odot$. Combining GAMA-II with data from G10-COSMOS we are able
to comment qualitatively on the shape of the GSMF down to masses as low as
$10^{6}$ $M_\odot$. Beyond the well known upturn seen in the GSMF at $10^{9.5}$
the distribution appears to maintain a single power-law slope from $10^9$ to
$10^{6.5}$. We calculate the stellar mass density parameter given our
best-estimate GSMF, finding $\Omega_\star= 1.66^{+0.24}_{-0.23}\pm0.97
h^{-1}_{70} \times 10^{-3}$, inclusive of random and systematic uncertainties.
