GRANNUS is an array of 5 seismometers in the north of the island of Ireland, operated by the Dublin Institute for Advanced Studies in collaboration with the Irish National Seismic Network, Geological Survey of Northern Ireland and Geological Survey Ireland. There are 5 broadband Nanometrics Trillium-120 PA seismometers with DIGOS Cube data loggers. The stations were installed in May and June 2023 and will run continuously for 2 years. GRANNUS improves the seismic station coverage in Northern Ireland and in the north of the Republic of Ireland. The data will be used to improve lithospheric scale subsurface imaging of Ireland and determine areas of high geothermal potential, in addition to seismicity analysis.