The Twin Impact Lunar Telescope network

Lunar impact flashes (LIFs) provide direct constraints on the flux and physical properties of meteoroids impacting the Earth–Moon system. Conventional LIF monitoring, performed mainly in the visible wavelength range, is strongly limited by lunar phase, sky brightness, and observing geometry, resulting in sparse temporal coverage and a low probability of detecting rare, high-energy events.

 

The Twin Impact Lunar Telescope (TILT) has been developed to overcome these limitations through a dedicated instrumental concept combined with a global observing strategy. Three telescopes will be deployed worldwide in the frame of the LISTEN FLASH ERC project. Each TILT node consists of two co-aligned telescopes optimized for high-cadence lunar observations in the near-infrared (NIR), where typical LIF thermal emission (∼2500–3000 K) peaks. Observations in the J band (~1.2 μm) benefit from increased photon flux and reduced atmospheric scattering compared to visible bands, enabling effective monitoring under bright sky conditions, including twilight and daytime. Simultaneous observations with twin telescopes allow robust discrimination between real lunar impact flashes and false positives, while a geographically distributed network of TILT stations provides near-continuous lunar coverage and redundancy against local observing constraints.

 

We present the TILT system design, observational strategy, and expected performance in terms of detection rates and impact energy thresholds. We also highlight the synergy of the TILT network with the lunar seismic experiments scheduled between 2026 and 2030. The TILT well-timed and located impacts will indeed provide known sources, enabling a direct computation of the seismic travel times for each pair of TILT LIF records and seismic records. This data set will  constraints on the thickness of the lunar crust and its early evolution.

 

The TILT-1, installed at the Observatory of Calern (Observatoire de la Côte d'Azur) was sucesfully tested during the Geminids meteor shower in December 2025. Recording of some tens of potential LIF, several of which being confrimed, was achieved.