Selected transformation

Method: General polynomial of degree 6

Remarks: Parameter values taken from TM75 to ETRS89 (1) (code 1041) assuming that ETRS89 is coincident with WGS 84 within the accuracy of the transformation. Use iteration for reverse transformation WGS 84 to TM75. May be emulated by NTv2 alternative code 6947.

Information source: OGP

Revision date: 2020-03-14


Unit: degree (supplier to define representation)

Geodetic CRS: TM75

Datum: Geodetic Datum of 1965

Ellipsoid: Airy Modified 1849

Prime meridian: Greenwich

Data source: EPSG

Information source: "The Irish Grid - A Description of the Co-ordinate Reference System" published by Ordnance Survey of Ireland, Dublin and Ordnance Survey of Northern Ireland, Belfast.

Revision date: 2004-01-06

Scope: Basis for topographic mapping.

Remarks: Uses Geodetic Datum of 1965 which should not be confused with the 1965 adjustment (TM65, datum code 6299 and CRS code 4299). Replaces OSNI52 (CRS code 4188) and TM65 (CRS code 4299). Replaced by IRENET95 (CRS code 4173).

Area of use: Ireland - onshore. United Kingdom (UK) - Northern Ireland (Ulster) - onshore.

Coordinate system: Ellipsoidal 2D CS. Axes: latitude, longitude. Orientations: north, east. UoM: degree

Center coordinates
-7.95 53.41

WGS84 bounds:
-10.56 51.39
-5.34 55.43

Ireland - onshore. United Kingdom (UK) - Northern Ireland (Ulster) - onshore.
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Definition: Well Known Text (WKT)

        SPHEROID["Airy Modified 1849",6377340.189,299.3249646]],

Definition: ESRI WKT


Definition: PROJ.4

+proj=longlat +a=6377340.189 +rf=299.3249646 +no_defs +type=crs

Definition: JavaScript (Proj4js)

proj4.defs("EPSG:4300","+proj=longlat +a=6377340.189 +rf=299.3249646 +no_defs +type=crs");

Definition: JSON

    "$schema": "https://proj.org/schemas/v0.4/projjson.schema.json",
    "type": "GeographicCRS",
    "name": "TM75",
    "datum": {
        "type": "GeodeticReferenceFrame",
        "name": "Geodetic Datum of 1965",
        "ellipsoid": {
            "name": "Airy Modified 1849",
            "semi_major_axis": 6377340.189,
            "inverse_flattening": 299.3249646
    "coordinate_system": {
        "subtype": "ellipsoidal",
        "axis": [
                "name": "Geodetic latitude",
                "abbreviation": "Lat",
                "direction": "north",
                "unit": "degree"
                "name": "Geodetic longitude",
                "abbreviation": "Lon",
                "direction": "east",
                "unit": "degree"
    "scope": "Basis for topographic mapping.",
    "area": "Ireland - onshore. United Kingdom (UK) - Northern Ireland (Ulster) - onshore.",
    "bbox": {
        "south_latitude": 51.39,
        "west_longitude": -10.56,
        "north_latitude": 55.43,
        "east_longitude": -5.34
    "id": {
        "authority": "EPSG",
        "code": 4300

Definition: GeoServer

4300=GEOGCS["TM75",DATUM["Geodetic_Datum_of_1965",SPHEROID["Airy Modified 1849",6377340.189,299.3249646]],PRIMEM["Greenwich",0],UNIT["degree",0.0174532925199433,AUTHORITY["EPSG","9122"]],AUTHORITY["EPSG","4300"]]

Definition: MapServer - MAPfile


Definition: Mapnik

<?xml version="1.0" encoding="utf-8"?>
<Map srs="+proj=longlat +a=6377340.189 +rf=299.3249646 +no_defs +type=crs">
	<Layer srs="+proj=longlat +a=6377340.189 +rf=299.3249646 +no_defs +type=crs">

Definition: SQL (PostGIS)

INSERT into spatial_ref_sys (srid, auth_name, auth_srid, proj4text, srtext) values ( 4300, 'EPSG', 4300, '+proj=longlat +a=6377340.189 +rf=299.3249646 +no_defs +type=crs', 'GEOGCS["TM75",DATUM["Geodetic_Datum_of_1965",SPHEROID["Airy Modified 1849",6377340.189,299.3249646]],PRIMEM["Greenwich",0],UNIT["degree",0.0174532925199433,AUTHORITY["EPSG","9122"]],AUTHORITY["EPSG","4300"]]');

Definition: OGC WKT

GEOGCS["TM75",DATUM["Geodetic_Datum_of_1965",SPHEROID["Airy Modified 1849",6377340.189,299.3249646]],PRIMEM["Greenwich",0],UNIT["degree",0.0174532925199433,AUTHORITY["EPSG","9122"]],AUTHORITY["EPSG","4300"]]

Definition: OGC WKT 2 (2019)

GEOGCRS["TM75",DATUM["Geodetic Datum of 1965",ELLIPSOID["Airy Modified 1849",6377340.189,299.3249646,LENGTHUNIT["metre",1]]],PRIMEM["Greenwich",0,ANGLEUNIT["degree",0.0174532925199433]],CS[ellipsoidal,2],AXIS["geodetic latitude (Lat)",north,ORDER[1],ANGLEUNIT["degree",0.0174532925199433]],AXIS["geodetic longitude (Lon)",east,ORDER[2],ANGLEUNIT["degree",0.0174532925199433]],USAGE[SCOPE["Basis for topographic mapping."],AREA["Ireland - onshore. United Kingdom (UK) - Northern Ireland (Ulster) - onshore."],BBOX[51.39,-10.56,55.43,-5.34]],ID["EPSG",4300]]