Dataset for the plots of "Photon counting intensity interferometry in the blue at a 0.5 m telescope"

We demonstrate the feasibility of intensity interferometry with fast single photon counting detectors at small telescopes by utilising a telescope of diameter of merely 0.5 m. The entire measurement setup, including collimation, optical filtering, and two single photon detectors, is attached directly to the telescope without the use of optical fibres, facilitated by the large area of our single photon detectors.

For digitisation and timing, we utilise a Time-To-Amplitude- Converter. Observing 𝛼 Lyrae (Vega) for a total exposure time of 32.4 h over the course of six nights, an auto-correlation signal with a contrast of (9.5 ± 2.7) × 10−3 and a coherence time of (0.34 ± 0.12) ps at a SNR of 2.8 is measured. The result fits well to preceding laboratory tests as well as expectations calculated from the optical and electronic characteristics of our measurement setup.