The Twin Impact Lunar Telescope network and Geminids 2025 observations

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

We present the Twin Impact Lunar Telescope (TILT) network, a new infrastructure dedicated to monitoring LIFs in the short-wave infrared (SwIR). Each station consists of twin robotic 0.4 m telescopes operating simultaneously in the J band (1.25 μm) and Z band (0.9 μm), allowing rejection of false positives and multi-wavelength characterization of impacts. The systems use high-speed cameras operating at 60-100 FPS together with dedicated acquisition software (pyfcam) enabling on-the-fly compression and FITS cube storage.

The telescopes incorporate elongated carbon-fiber tubes and dedicated baffles allowing daylight observations of the Moon, substantially increasing observing time. TILT-1 is currently installed at Calern Observatory (Observatoire de la Côte d’Azur), while TILT-2 and TILT-3 are under construction. The objective is to deploy at least three stations at separated longitudes to maximize lunar coverage and increase detection of energetic LIFs.

The TILT network will support the Advanced ERC project LISTEN FLASH, which aims to combine telescopic observations of LIFs with lunar seismic detections. This unique approach will provide new constraints on the luminous efficiency of hypervelocity impacts, the flux of small bodies in cislunar space, and the properties of the lunar regolith and crust’s thickness.

We will also present some results from the TILT observations of the Geminids meteor stream in Dec 2025.  We detected 53 potential impact flashes and confirmed 11 of them through multi-frame observations, and independent detections by other observers. Our confirmed events range between magnitude +7.5 and +10.4, primarily in the V- and R-band. We obtained a higher rate of observations per hour than the expected values from existing campaigns, highlighting the importance of high-ZHR meteoroid streams for observing LIFs.