The first shear measurements from precision weak lensing
  We present an end-to-end methodology to measure the effects of weak lensing
on individual galaxy-galaxy systems exploiting their kinematic information.
Using this methodology, we have measured a shear signal from the velocity
fields of 18 weakly-lensed galaxies. We selected a sample of systems based only
on the properties of the sources, requiring them to be bright (apparent
$i$-band magnitude $ < 17.4$) and in the nearby Universe ($z < 0.15$). We have
observed the velocity fields of the sources with WiFeS, an optical IFU on a
2.3m telescope, and fitted them using a simple circular motion model with an
external shear. We have measured an average shear of $\langle \gamma \rangle =
0.020 \pm 0.008$ compared to a predicted $\langle \gamma_{pred} \rangle =
0.005$ obtained using median stellar-to-halo relationships from the literature.
While still a statistical approach, our results suggest that this new weak
lensing methodology can overcome some of the limitations of traditional
stacking-based techniques. We describe in detail all the steps of the
methodology and make publicly available all the velocity maps for the
weakly-lensed sources used in this study.
