Present and planned large field-of-view (FoV) gamma-ray observatories are installed in the Northern Hemisphere, missing, in particular, the galactic center, and have energy thresholds above 0.5 TeV. The goal of the LATTES group is to participate in the design, prototyping and construction of a a ground array able to monitor the Southern gamma-ray sky above 100 GeV, bringing to ground the wide field-of-view and large duty cycle observations characteristic of satellites, with comparable sensitivity and a cost one order of magnitude lower. Such an instrument will be a powerful time-variance explorer filling an empty space in the global multi-messenger network of gravitational waves, electromagnetic telescopes in different wavelengths, and neutrino observatories. It will be able to issue pointing alerts to the large next-generation imaging atmospheric Cherenkov telescope array, CTA, being largely complementary to such observatories. It will collect abundant and highly relevant data and play a fundamental role in the search for emissions from extended regions, as the Fermi bubbles or dark matter annihilation regions.

A proof-of-concept design based on a compact air shower array of hybrid detector units composed by small water Cherenkov detectors (WCD) and resistive plate chambers (RPC) was developed in 2016-17 and published at the beginning of 2018. A proposal submitted to FCT was approved in May 2018 and provides support to the project activities for three years. We are currently working in a new layout concept, with a central core of WCDs equipped with RPC muon hodoscopes surrounded by a large number of WCDs. This layout will allow to cover a considerably larger area, thus increasing the sensitivity of the observatory.

Recently, several groups in the world that are developing similar projects started exchanging ideas and expertise, and for the first time general meetings on a future wide FoV gamma-ray detector for the southern hemisphere were organised. In a meeting held in Lisbon in May 2019 the decision was taken to create an international collaboration for R&D on such an observatory. The new collaboration joins different groups and communities that were already involved in R&D in this field, coming both from currently running experiments and from new R&D projects. The collaboration agreement is expected to be signed by July 1st by a minimum of four countries.

Group webpage at LIP