LEM-X: an all sky monitor for the Moon's surface

LEM-X is an all-sky X-ray observatory proposed for the surface of the Moon. Its primary scientific goal is to enhance multi-messenger astrophysics by detecting and monitoring high-energy transient phenomena and variable X-ray sources across the sky. The building block of LEM-X is a pair of coded aperture cameras, able to image the sky in a field of view of 2 sr (FWZR) with a source location accuracy of 1 arcmin. The LEM-X instrument envisages multiple camera pairs in a dome-shaped structure, with each camera designed to achieve a sensitivity better than 5 mCrab in 50 ks and 1 Crab in 1 s in a wide energy band (2–50 keV). The sensitive elements of LEM-X are large area linear Silicon Drift Detectors (SDDs) read-out by custom low-noise ASICs, which provide excellent spectral-timing performance. The energy resolution at room temperature is better than 350 eV FWHM at 6 keV, with 10 µs time resolution. In this contribution, we describe the LEM-X design and report about its development status.