Cosmic Gravitational Shear from the HST Medium Deep Survey

We present a measurement of cosmic shear on scales ranging from $10\text{arcsec}$ to $2\text{arcmin}$ in 347 WFPC2 images of random fields. Our result is based on shapes measured via image fitting and on a simple statistical technique; careful calibration of each step allows us to quantify our systematic uncertainties and to measure the cosmic shear down to very small angular scales. The WFPC2 images provide a robust measurement of the cosmic shear signal decreasing from $5.2$ at $10\text{arcsec}$ to $2.2$ at $130\text{arcsec}$.