| Description | Hanbury Brown first tested his intensity interferometer on the star Sirius. He published the observational details (gathered in November and December 1955) and the results a year later in a paper (with the mathematician R Q Twiss). Earlier in 1956, Hanbury Brown and Twiss had elucidated the principle behind these measurements, arguing on the basis of a laboratory experiment that the time of arrival of photons at two separate detectors was correlated (Hanbury Brown-Twiss effect). Their subsequent publication of the Sirius data demonstrated how this phenomenon could be used in an interferometer to measure the apparent angular diameter of bright visual stars. The Sirius-paper provided a practical vindication of the then much-disputed Hanbury Brown-Twiss effect. |