Intensity Interferometry at Calern and beyond: progress report

TL;DR

This paper reports on recent technical improvements and successful observational campaigns of the I2C intensity interferometer, enhancing high angular resolution measurements of stars using various small telescopes and adaptive optics.

Contribution

It introduces new technical enhancements to the I2C interferometer, including adaptive optics integration and multi-telescope testing, advancing stellar high-resolution observation capabilities.

Findings

Successful integration of tip-tilt adaptive optics for light stabilization.

Effective testing with multiple telescopes including VLTI auxiliary units.

Achieved temporal and spatial correlation measurements of three stars.

Abstract

We present the current status of the I2C stellar intensity interferometer used towards high angular resolution observations of stars in visible wavelengths. In these proceedings, we present recent technical improvements to the instrument, and share results from ongoing campaigns using arrays of small diameter optical telescopes. A tip-tilt adaptive optics unit was integrated into the optical system to stabilize light injection into an optical fiber. The setup was successfully tested with several facilities on the Calern Plateau site of the Observatoire de la C\^ote d'Azur. These include one of the 1 m diameter telescopes of the C2PU observatory, a portable 1 m diameter telescope, and also the 1.5 m M\'eO telescope. To better constrain on-sky measurements, the spectral transmission of instrument was characterized in the laboratory using a high resolution spectrograph. The system was also tested with two of the auxiliary telescopes of the VLTI resulting in successful temporal and spatial correlation measurements of three stars.