A telescopic instrument for direct astronomical lightspeed measurements

A fibre-optic time-of-flight instrument based on a modified Fizeau apparatus has been developed to measure the speed of light emanating from astronomical objects. The instrument is optimized for low photon flux sources. Lightspeed measurements from 11 nearby stars are reported, with a mean value of (2.98 ? 0.03) ? 108 m?s?1. These are the first direct photon velocity measurements for sources outside the solar system.