2018MNRAS.480..245G

The present article reports on the first spatial intensity interferometry measurements on stars since the observations at Narrabri Observatory by Hanbury Brown et al. in the 1970s. Taking advantage of the progresses in recent years on photon-counting detectors and fast electronics, we were able to measure the zero-time delay intensity correlation g⁽²⁾(τ = 0, r) between the light collected by two 1-m optical telescopes separated by 15 m. Using two marginally resolved stars (α Lyr and β Ori) with R magnitudes of 0.01 and 0.13, respectively, we demonstrate that 4-h correlation exposures provide reliable visibilities, whilst a significant loss of contrast is found on α Aur, in agreement with its binary-star nature.