KiDS-i-800: comparing weak gravitational lensing measurements from same-sky surveys
Heymans, C.; Wolf, C.; Lidman, C.; Choi, A.; Hoekstra, H.; Glazebrook, K.; Schneider, P.; Joachimi, B.; Hildebrandt, H.; Erben, T.; de Jong, J. T. A.; Viola, M.; Joudaki, S.; Kuijken, K.; Blake, C.; Klaes, D.; Miller, L.; Morrison, C. B.; Amon, A.; Napolitano, N.; van Uitert, E.; Parkinson, D.; Kannawadi, A.; Irisarri, N.
United Kingdom, Germany, Australia, Netherlands, United States, Italy
Abstract
We present a weak gravitational lensing analysis of 815 deg2 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 data set (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 ± 4 per cent. 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 ± 5 per cent when the KiDS-i-800 source redshift distribution is calibrated using either spectroscopic redshifts, or the 30-band photometric redshifts from the COSMOS survey.