Related papers: Simultaneous Two Colour Intensity Interferometry w…
Intensity interferometry for astrophysical observations has gained increasing interest in the last decade. The method of correlating photon fluxes at different telescopes for high resolution astronomy without access to the phase of the…
Imaging Atmospheric Cherenkov Telescopes have long been viewed as potential light collectors to be used for long baseline optical intensity interferometry observations. Intensity interferometry, as implemented with Cherenkov telescopes, is…
High angular resolution observations at optical wavelengths provide valuable insights in stellar astrophysics, directly measuring fundamental stellar parameters, and probing stellar atmospheres, circumstellar disks, elongation of rapidly…
H.E.S.S. is a system of Imaging Atmospheric Cherenkov Telescopes (IACTs) measuring cosmic gamma-rays with very high energies in Namibia. Extending the array with a fifth telescope with a mirror area of 600 m$^2$ leads to a lower energy…
In recent years, a new generation of optical intensity interferometers has emerged, leveraging the existing infrastructure of Imaging Atmospheric Cherenkov Telescopes (IACTs). The MAGIC telescopes host the MAGIC-SII system (Stellar…
The H.E.S.S. (High Energy Stereoscopic System) phase I is comprised of four Imaging Atmospheric Cherenkov telescopes, for observation of galactic and cosmic sources of very high energy gamma rays. Its installation in the Khomas highlands,…
Observations of binary systems obtained recently with the High Energy Stereoscopic System (H.E.S.S) of Cherenkov telescopes are reported. The outcomes of a detailed observation campaign on PSR B1259-63 during its periastron passage in 2014…
The H.E.S.S. instrument consists of four 13 m (H.E.S.S. I) and one 28 m diameter (H.E.S.S. II) Atmospheric Cherenkov Telescopes (ACTs) located in the Khomas Highland in Namibia, 1800 m above sea level. The H.E.S.S. I array began operations…
The VERITAS Imaging Atmospheric Cherenkov Telescope array (IACT) was augmented in 2019 with high-speed focal plane electronics to create a new Stellar Intensity Interferometry (SII) observational capability (VERITAS-SII, or VSII). VSII…
In the 1970s, the Narrabri intensity interferometer was used to measure 32 stellar diameters; some as small as 0.4 milli-arc-seconds (mas). The interferometer consisted of a pair of 6.5m telescopes with relatively crude optics, similar to…
The VERITAS Imaging Air Cherenkov Telescope (IACT) array was augmented in 2019 with high-speed focal plane electronics to allow its use for Stellar Intensity Interferometry (SII) observations. Since January 2019, the VERITAS Stellar…
The imminent availability of large arrays of large light collectors deployed to exploit atmospheric Cherenkov radiation for gamma-ray astronomy at more than 100GeV, motivates the growing interest in application of intensity interferometry…
We report on observations of the extended environment of the bright Be star $\gamma$-Cas performed using intensity interferometry measurements within its H$\alpha$ emission line. These observations were performed using a modified version of…
The High Energy Stereoscopic System (H.E.S.S.) is an array of imaging atmospheric Cherenkov telescopes (IACTs) located in the Khomas Highland in Namibia. It consists of four 12-m telescopes (CT1-4), which started operations in 2003, and a…
We present measurements of the second order spatial coherence function of thermal light sources using Hanbury-Brown and Twiss interferometry with a digital correlator. We demonstrate that intensity fluctuations between orthogonal…
Imaging Atmospheric Cherenkov Telescopes (IACTs) currently in operation feature large mirrors and order of 1 ns time response to signals of a few photo-electrons produced by optical photons. This means that they are ideally suited for…
The closure phase, the sum of the three Fourier phases in a telescope triangle, is an important tool in astronomical interferometry, helping to reconstruct the geometries of the observed objects. While already established in amplitude…
Most neighboring stars are still detected as point sources and are beyond the angular resolution reach of current observatories. Methods to improve our understanding of stars at high angular resolution are investigated. Air Cherenkov…
We have constructed an optical photometer with microsecond time resolution, which is currently being operated on one of the H.E.S.S. telescopes. H.E.S.S. is an array of four Cherenkov telescopes, each with a 107 m^2 mirror, located in the…
In recent years, intensity interferometry has seen renewed interest and successful application at Imaging Atmospheric Cherenkov Telescope arrays. These measurements are usually performed during bright moon periods while the instruments'…