 19.March 1999
19.March 1999Coordinate Reference Systems Northern Ireland 
The Irish 
Grid (Ireland 1975):  
Ellipsoid: Airy Modified 
Map Projection: Transverse Mercator 
Central Point/Datum: ? 
    
    | Scale Mapping:  | 
    
    | Irish National Grid (1975) | 
    
    |  | 
Poolberg Datum 
(1837) 
Reference Point: Poolberg Lighthouse in Dublin Bay 
Reference Level: Poolberg Lighthouse on April 8.th, 1837 
Geoid: - 
Belfast Datum 
(1952) 
Reference Point: Tide Gauge at Clarendon Dock Belfast  
Reference Level: Mean Sea Level (MSL) Belfast (Average 1951-56) 
Geoid: - 
Malin Head 
Datum (1957) 
Reference Point: Tidal Station at Malin Head in Co. Donegal 
Reference Level: Mean Sea Level Malin Head 
Geoid: -