Detection, size, measurement and structural analysis limits for the
  2MASS, UKIDSS-LAS & VISTA VIKING surveys
  The 2MASS, UKIDSS-LAS and VISTA VIKING surveys have all now observed the GAMA
9hr region in the $K_s$ band. Here we compare the detection rates, photometry,
basic size measurements, and single-component GALFIT structural measurements
for a sample of 37,591 galaxies. We explore the sensitivity limits where the
data agree for a variety of issues including: detection, star-galaxy
separation, photometric measurements, size and ellipticity measurements, and
S\'{e}rsic measurements. We find that 2MASS fails to detect at least 20% of the
galaxy population within all magnitude bins, however for those that are
detected we find photometry is robust ($\pm$ 0.2 mag) to 14.7 AB mag and
star-galaxy separation to 14.8 AB mag. For UKIDSS-LAS we find incompleteness
starts to enter at a flux limit of 18.9 AB mag, star-galaxy separation is
robust to 16.3 AB mag and structural measurements are robust to 17.7 AB mag.
VISTA VIKING data is complete to approximately 20.0 AB mag and structural
measurements appear robust to 18.8 AB mag.
