Stellar Intensity Interferometry Workshop 2025

Session

SII with IACTs

14 Oct 2025, 16:00

Research Campus Waischenfeld (Germany) of the Fraunhofer Society

Conveners

SII with IACTs

• Joachim von Zanthier (QOQI, Friedrich-Alexander-Universität Erlangen-Nürnberg)

SII with IACTs

• Pedro Ivo Silva Batista (Erlangen Centre for Astroparticle Physics)

38. State-of-the-art space-based quantum communication

Christoph Marquardt (Max Planck Institute for the Science of Light)

14/10/2025, 16:00

Invited talk

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20. Analysis techniques for pushing the limits of stellar intensity interferometry

John Scott (The Ohio State University)

14/10/2025, 16:35

Contributed talk

We recently used the VERITAS SII (Stellar Intensity Interferometry) system to extend SII measurements from round to oblate photospheres of stars. We now aim to push SII further by measuring more complex sources such as Spica, a spectroscopic binary star with a period of approximately 4 days. Spica was first measured by Hanbury Brown using the Narrabri Interferometer in 1971 but has not been...

17. Modeling preliminary VERITAS-SII measurements on Spica

Prof. Michael Lisa (Ohio State University)

14/10/2025, 16:50

Invited talk

The VERITAS collaboration has performed SII measurements on the system Alpha Virginis (Spica) using multiple telescope pairs over several nights. We compare these preliminary data with expectations for various sources, including a round star, a single elliptical star, and a binary star system. We discuss also the challenges for presenting multiple-baseline SII measurements (including,...

16. Enabling Intensity Interferometry with the CTAO

Jonathan Biteau (Université Paris-Saclay, CNRS/IN2P3, IJCLab)

14/10/2025, 17:25

Invited talk

The Cherenkov Telescope Array Observatory (CTAO) is a new generation of telescope arrays for gamma-ray astronomy. The telescopes are designed to collect ultraviolet to red Cherenkov photons from extensive air showers with nanosecond sampling. The total mirror area of the telescopes exceeds that of the Extremely Large Telescope at each CTAO site: Paranal in the Atacama Desert (CTAO-South) and...

7. Optical intensity interferometry observations with the MAGIC and CTAO-North LST telescopes

Tarek Hassan Collado (CIEMAT)

15/10/2025, 09:00

Invited talk

In addition to their gamma-ray observations in the very high energy regime (20 GeV - 100 TeV), the two 17-m MAGIC telescopes are ideal instruments for optical stellar intensity interferometer (SII), and have been routinely performing observations in SII mode for the last six years. The calibration and validation of the setup, alongside the first measurement of the stellar angular diameter of...

15. The Butterfly camera: expanding sensitivity and angular coverage of IACTs as stellar intensity interferometers

Fernando Frías (Instituto de Astrofísica de Canarias (IAC))

15/10/2025, 09:35

Contributed talk

Imaging Atmospheric Cherenkov Telescopes (IACTs) have recently shown great potential as optical intensity interferometers. However, due to their design there are some intrinsic limitations to improving their sensitivity, such as their low focal ratios. Implementing the 'I3T concept', in which sets of facets of the primary mirror (submirrors) are focused onto different pixels of the camera, on...

22. Sub-nanosecond, very narrow band intensity interferometry on the ASTRI Mini-Array

Luca Zampieri (INAF-Astronomical Observatory of Padova)

15/10/2025, 09:50

Invited talk

Despite the extraordinary leap forward obtained with current implementations on Imaging Air Cherenkov Telescopes (IACTs), which take advantage from the huge photon statistics, intensity interferometry on IACTs has to cope with the poor optical quality and large numerical aperture of the optics, which is a limiting factor for observations in narrow spectral bands and with sub-nanosecond...