The Irish grid reference system is a system of geographic grid references used for paper mapping in Ireland (both Northern Ireland and the Republic of Ireland).[1] The Irish grid partially overlaps the British grid, and uses a similar co-ordinate system but with a meridian more suited to its westerly location.
The national grid referencing system was devised by the Ordnance Survey, and is heavily used in their survey data, and in maps (whether published by the Ordnance Survey of Ireland, the Ordnance Survey of Northern Ireland or commercial map producers) based on those surveys. Additionally grid references are commonly quoted in other publications and data sources, such as guide books or government planning documents.
In 2001, the Ordnance Survey of Ireland and the Ordnance Survey of Northern Ireland jointly implemented a new coordinate system for Ireland called Irish Transverse Mercator, or ITM, a location-specific optimisation of UTM, which runs in parallel with the existing Irish grid system. In both systems, the true origin is at 53° 30' N, 8° W[2] — a point in Lough Ree, close to the western (Co. Roscommon) shore, whose grid reference is N000500. The ITM system was specified so as to provide precise alignment with modern high-precision global positioning receivers.
Grid letters
Irish grid
The area of Ireland is divided into 25 squares, measuring 100 by 100 km (62 by 62 mi), each identified by a single letter. The squares are numbered A to Z with I being omitted. Seven of the squares do not actually cover any land in Ireland: A, E, K, P, U, Y and Z.
Eastings and northings
Within each square, eastings and northings from the origin (south west corner) of the square are given numerically. For example, G0305 means 'square G, 3 km (1.9 mi) east, 5 km (3.1 mi) north'. A location can be indicated to varying resolutions numerically, usually from two digits in each coordinate (for a 1 km (0.62 mi) square) through to five (for a 1 m (3 ft 3 in)) square; the most common usage is the six figure grid reference, employing three digits in each coordinate to determine a 100 m (330 ft) square.
Coordinates may also be given relative to the origin of the entire 500 by 500 km (310 by 310 mi) grid (in the format easting, northing). For example, the location of the Spire of Dublin on O'Connell Street may be given as 315904, 234671 as well as O1590434671. Coordinates in this format must never be truncated, because, for example, 31590, 23467 is also a valid location.
Summary parameters of the Irish Grid coordinate system
Leahy, Derek (September 26, 2008). . Ordnance Survey Ireland : 185 years of innovation in mapping. Dublin: Ordnance Survey Ireland. Archived from the original on September 11, 2009. Retrieved 14 August 2009.
External links
The Irish Grid - A Description of the Co-ordinate Reference System used in Ireland PDF (358kB) on the Irish Grid from OSi.
PDF (221KB) detailing GPS to Irish Grid conversions
OSI online coordinate converter tool
Clickable webmap that shows Irish grid references
LatLong <> OSi Grid Ref converts & presents in many formats, generates specific links to that location for several useful map web pages - 1840 - present. LatLong WSG84 <> GB, Ireland (inc NI) and Chanel Islands (30U) GR formats recognised. Distance measure for dog-leg routes & area calculations.
April 29, 2023
irish, grid, reference, system, system, geographic, grid, references, used, paper, mapping, ireland, both, northern, ireland, republic, ireland, irish, grid, partially, overlaps, british, grid, uses, similar, ordinate, system, with, meridian, more, suited, wes. The Irish grid reference system is a system of geographic grid references used for paper mapping in Ireland both Northern Ireland and the Republic of Ireland 1 The Irish grid partially overlaps the British grid and uses a similar co ordinate system but with a meridian more suited to its westerly location Contents 1 Usage 2 2001 recasting the ITM grid 3 Grid letters 4 Eastings and northings 5 Summary parameters of the Irish Grid coordinate system 6 Notes 7 References 8 External linksUsage EditIn general neither Ireland nor Great Britain uses latitude or longitude in describing internal geographic locations Instead grid reference systems are used for mapping The national grid referencing system was devised by the Ordnance Survey and is heavily used in their survey data and in maps whether published by the Ordnance Survey of Ireland the Ordnance Survey of Northern Ireland or commercial map producers based on those surveys Additionally grid references are commonly quoted in other publications and data sources such as guide books or government planning documents 2001 recasting the ITM grid EditMain article Irish Transverse Mercator In 2001 the Ordnance Survey of Ireland and the Ordnance Survey of Northern Ireland jointly implemented a new coordinate system for Ireland called Irish Transverse Mercator or ITM a location specific optimisation of UTM which runs in parallel with the existing Irish grid system In both systems the true origin is at 53 30 N 8 W 2 a point in Lough Ree close to the western Co Roscommon shore whose grid reference is N000500 The ITM system was specified so as to provide precise alignment with modern high precision global positioning receivers Grid letters Edit Irish grid The area of Ireland is divided into 25 squares measuring 100 by 100 km 62 by 62 mi each identified by a single letter The squares are numbered A to Z with I being omitted Seven of the squares do not actually cover any land in Ireland A E K P U Y and Z Eastings and northings EditWithin each square eastings and northings from the origin south west corner of the square are given numerically For example G0305 means square G 3 km 1 9 mi east 5 km 3 1 mi north A location can be indicated to varying resolutions numerically usually from two digits in each coordinate for a 1 km 0 62 mi square through to five for a 1 m 3 ft 3 in square the most common usage is the six figure grid reference employing three digits in each coordinate to determine a 100 m 330 ft square Coordinates may also be given relative to the origin of the entire 500 by 500 km 310 by 310 mi grid in the format easting northing For example the location of the Spire of Dublin on O Connell Street may be given as 315904 234671 as well as O1590434671 Coordinates in this format must never be truncated because for example 31590 23467 is also a valid location Summary parameters of the Irish Grid coordinate system EditSpheroid Airy Modified Datum 1965 Map projection Transverse Mercator Latitude of Origin 53 30 00 N Longitude of Origin 8 00 00 W Scale Factor 1 000 035 False Easting 200000 m False Northing 250000 mNotes Edit How to Use Map Scales and Grids OSI Irish Grid Reference System References EditLeahy Derek September 26 2008 Irish Grid Reference System Ordnance Survey Ireland 185 years of innovation in mapping Dublin Ordnance Survey Ireland Archived from the original on September 11 2009 Retrieved 14 August 2009 External links EditThe Irish Grid A Description of the Co ordinate Reference System used in Ireland PDF 358kB on the Irish Grid from OSi PDF 221KB detailing GPS to Irish Grid conversions A detailed 42 page PDF file including history and map of the Irish grid and its links to Britain A two page article for the American Society for Photogrammetry and Remote Sensing summarising the above History and overview of the system from OSI OSI online coordinate converter tool Clickable webmap that shows Irish grid references LatLong lt gt OSi Grid Ref converts amp presents in many formats generates specific links to that location for several useful map web pages 1840 present LatLong WSG84 lt gt GB Ireland inc NI and Chanel Islands 30U GR formats recognised Distance measure for dog leg routes amp area calculations Retrieved from https en wikipedia org w index php title Irish grid reference system amp oldid 1081273746, wikipedia, wiki, book, books, library,
