KiDS-i-800: Comparing weak gravitational lensing measurements in
  same-sky surveys
  We present a weak gravitational lensing analysis of 815 square degree of
$i$-band imaging from the Kilo-Degree Survey (KiDS-$i$-800). In contrast to the
deep $r$-band observations, which take priority during excellent seeing
conditions and form the primary KiDS dataset (KiDS-$r$-450), the complementary
yet shallower KiDS-$i$-800 spans a wide range of observing conditions. The
overlapping KiDS-$i$-800 and KiDS-$r$-450 imaging therefore provides a unique
opportunity to assess the robustness of weak lensing measurements. In our
analysis, we introduce two new `null' tests. The `nulled' two-point shear
correlation function uses a matched catalogue to show that the calibrated
KiDS-$i$-800 and KiDS-$r$-450 shear measurements agree at the level of $1 \pm
4$\%. We use five galaxy lens samples to determine a `nulled' galaxy-galaxy
lensing signal from the full KiDS-$i$-800 and KiDS-$r$-450 surveys and find
that the measurements agree to $7 \pm 5$\% when the KiDS-$i$-800 source
redshift distribution is calibrated using either spectroscopic redshifts, or
the 30-band photometric redshifts from the COSMOS survey.
