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Name: NAD27 to NAD83 (7)
Method: NADCON5 (2D)
Grid Files: nadcon5.nad27.nad83_1986.conus.lat.trn.20160901.b nadcon5.nad27.nad83_1986.conus.lon.trn.20160901.b
Remarks: NADCON5 method expects longitudes 0-360°; source and target CRS longitudes in range ±180°. Accuracy at 67% confidence level is 0.15m onshore, 1m nearshore and undetermined farther offshore. For application in Gulf of Mexico refer to IOGP report 373-26.
Information source: National Geodetic Survey, www.ngs.noaa.gov
Revision date: 2021-10-18
Unit: US survey foot
Geodetic CRS: NAD27
Datum: North American Datum 1927
Ellipsoid: Clarke 1866
Prime meridian: Greenwich
Data source: EPSG
Information source: OGP
Revision date: 2025-07-10
Scope: No official usage.
Remarks: This system is NOT used for oil industry purposes. Use NAD27 / Louisiana South (CRS code 26782) in state waters and on LA OCS shelf and NAD27 / BLM (CRS codes 32065-66) in OCS deep water protraction areas.
Area of use: United States (USA) - central Gulf of Mexico outer continental shelf (GoM OCS) planning area, deep water portion.
Coordinate system: Cartesian 2D CS. Axes: easting, northing (X,Y). Orientations: east, north. UoM: ftUS.
&stroke=red&width=2&path=23.82,-124.79|49.38,-124.79|49.38,-66.91|23.82,-66.91|23.82,-124.79)
Center coordinates
inf inf
Projected bounds:
inf inf
inf inf
WGS84 bounds:
-124.79 23.82
-66.91 49.38
Definition: OGC Well Known Text 2 (2019)
BOUNDCRS[ SOURCECRS[ PROJCRS["NAD27 / Louisiana Offshore", BASEGEOGCRS["NAD27", DATUM["North American Datum 1927", ELLIPSOID["Clarke 1866",6378206.4,294.978698213898, LENGTHUNIT["metre",1]]], PRIMEM["Greenwich",0, ANGLEUNIT["degree",0.0174532925199433]], ID["EPSG",4267]], CONVERSION["Louisiana CS27 Offshore zone", METHOD["Lambert Conic Conformal (2SP)", ID["EPSG",9802]], PARAMETER["Latitude of false origin",25.6666666666667, ANGLEUNIT["degree",0.0174532925199433], ID["EPSG",8821]], PARAMETER["Longitude of false origin",-91.3333333333333, ANGLEUNIT["degree",0.0174532925199433], ID["EPSG",8822]], PARAMETER["Latitude of 1st standard parallel",27.8333333333333, ANGLEUNIT["degree",0.0174532925199433], ID["EPSG",8823]], PARAMETER["Latitude of 2nd standard parallel",26.1666666666667, ANGLEUNIT["degree",0.0174532925199433], ID["EPSG",8824]], PARAMETER["Easting at false origin",2000000, LENGTHUNIT["US survey foot",0.304800609601219], ID["EPSG",8826]], PARAMETER["Northing at false origin",0, LENGTHUNIT["US survey foot",0.304800609601219], ID["EPSG",8827]]], CS[Cartesian,2], AXIS["easting (X)",east, ORDER[1], LENGTHUNIT["US survey foot",0.304800609601219]], AXIS["northing (Y)",north, ORDER[2], LENGTHUNIT["US survey foot",0.304800609601219]], USAGE[ SCOPE["No official usage."], AREA["United States (USA) - central Gulf of Mexico outer continental shelf (GoM OCS) planning area, deep water portion."], BBOX[25.58,-93.38,29.35,-86.53]], ID["EPSG",32099]]], TARGETCRS[ GEOGCRS["NAD83", DATUM["North American Datum 1983", ELLIPSOID["GRS 1980",6378137,298.257222101, 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["Geodesy."], AREA["North America - onshore and offshore: Canada - Alberta; British Columbia; Manitoba; New Brunswick; Newfoundland and Labrador; Northwest Territories; Nova Scotia; Nunavut; Ontario; Prince Edward Island; Quebec; Saskatchewan; Yukon. Puerto Rico. United States (USA) - Alabama; Alaska; Arizona; Arkansas; California; Colorado; Connecticut; Delaware; Florida; Georgia; Hawaii; Idaho; Illinois; Indiana; Iowa; Kansas; Kentucky; Louisiana; Maine; Maryland; Massachusetts; Michigan; Minnesota; Mississippi; Missouri; Montana; Nebraska; Nevada; New Hampshire; New Jersey; New Mexico; New York; North Carolina; North Dakota; Ohio; Oklahoma; Oregon; Pennsylvania; Rhode Island; South Carolina; South Dakota; Tennessee; Texas; Utah; Vermont; Virginia; Washington; West Virginia; Wisconsin; Wyoming. US Virgin Islands. British Virgin Islands."], BBOX[14.92,167.65,86.46,-40.73]], ID["EPSG",4269], REMARK["Longitude is POSITIVE EAST. The adjustment included connections to Greenland and Mexico but the system was not adopted there. For applications with an accuracy of better than 1m replaced by NAD83(HARN) in the US and PRVI and by NAD83(CSRS) in Canada."]]], ABRIDGEDTRANSFORMATION["NAD27 to NAD83 (7)", METHOD["NADCON5 (2D)", ID["EPSG",1074]], PARAMETERFILE["Latitude difference file","nadcon5.nad27.nad83_1986.conus.lat.trn.20160901.b"], PARAMETERFILE["Longitude difference file","nadcon5.nad27.nad83_1986.conus.lon.trn.20160901.b"], USAGE[ SCOPE["Geodesy."], AREA["United States (USA) - CONUS onshore - Alabama; Arizona; Arkansas; California; Colorado; Connecticut; Delaware; Florida; Georgia; Idaho; Illinois; Indiana; Iowa; Kansas; Kentucky; Louisiana; Maine; Maryland; Massachusetts; Michigan; Minnesota; Mississippi; Missouri; Montana; Nebraska; Nevada; New Hampshire; New Jersey; New Mexico; New York; North Carolina; North Dakota; Ohio; Oklahoma; Oregon; Pennsylvania; Rhode Island; South Carolina; South Dakota; Tennessee; Texas; Utah; Vermont; Virginia; Washington; West Virginia; Wisconsin; Wyoming. US Gulf of Mexico offshore continental shelf (GoM OCS)."], BBOX[23.82,-124.79,49.38,-66.91]], ID["EPSG",8555], REMARK["NADCON5 method expects longitudes 0-360°; source and target CRS longitudes in range ±180°. Accuracy at 67% confidence level is 0.15m onshore, 1m nearshore and undetermined farther offshore. For application in Gulf of Mexico refer to IOGP report 373-26."]]]
Definition: JSON
{ "$schema": "https://proj.org/schemas/v0.7/projjson.schema.json", "type": "BoundCRS", "source_crs": { "type": "ProjectedCRS", "name": "NAD27 / Louisiana Offshore", "base_crs": { "type": "GeographicCRS", "name": "NAD27", "datum": { "type": "GeodeticReferenceFrame", "name": "North American Datum 1927", "ellipsoid": { "name": "Clarke 1866", "semi_major_axis": 6378206.4, "semi_minor_axis": 6356583.8 } }, "coordinate_system": { "subtype": "ellipsoidal", "axis": [ { "name": "Geodetic latitude", "abbreviation": "Lat", "direction": "north", "unit": "degree" }, { "name": "Geodetic longitude", "abbreviation": "Lon", "direction": "east", "unit": "degree" } ] }, "id": { "authority": "EPSG", "code": 4267 }, "remarks": "Note: this CRS includes longitudes which are POSITIVE EAST. Replaced by NAD27(76) (code 4608) in Ontario, CGQ77 (code 4609) in Quebec, Mexican Datum of 1993 (code 4483) in Mexico, NAD83 (code 4269) in Canada (excl. Ontario & Quebec) & USA." }, "conversion": { "name": "Louisiana CS27 Offshore zone", "method": { "name": "Lambert Conic Conformal (2SP)", "id": { "authority": "EPSG", "code": 9802 } }, "parameters": [ { "name": "Latitude of false origin", "value": 25.6666666666667, "unit": "degree", "id": { "authority": "EPSG", "code": 8821 } }, { "name": "Longitude of false origin", "value": -91.3333333333333, "unit": "degree", "id": { "authority": "EPSG", "code": 8822 } }, { "name": "Latitude of 1st standard parallel", "value": 27.8333333333333, "unit": "degree", "id": { "authority": "EPSG", "code": 8823 } }, { "name": "Latitude of 2nd standard parallel", "value": 26.1666666666667, "unit": "degree", "id": { "authority": "EPSG", "code": 8824 } }, { "name": "Easting at false origin", "value": 2000000, "unit": { "type": "LinearUnit", "name": "US survey foot", "conversion_factor": 0.304800609601219 }, "id": { "authority": "EPSG", "code": 8826 } }, { "name": "Northing at false origin", "value": 0, "unit": { "type": "LinearUnit", "name": "US survey foot", "conversion_factor": 0.304800609601219 }, "id": { "authority": "EPSG", "code": 8827 } } ] }, "coordinate_system": { "subtype": "Cartesian", "axis": [ { "name": "Easting", "abbreviation": "X", "direction": "east", "unit": { "type": "LinearUnit", "name": "US survey foot", "conversion_factor": 0.304800609601219 } }, { "name": "Northing", "abbreviation": "Y", "direction": "north", "unit": { "type": "LinearUnit", "name": "US survey foot", "conversion_factor": 0.304800609601219 } } ] }, "id": { "authority": "EPSG", "code": 32099 } }, "target_crs": { "type": "GeographicCRS", "name": "NAD83", "datum": { "type": "GeodeticReferenceFrame", "name": "North American Datum 1983", "ellipsoid": { "name": "GRS 1980", "semi_major_axis": 6378137, "inverse_flattening": 298.257222101 } }, "coordinate_system": { "subtype": "ellipsoidal", "axis": [ { "name": "Geodetic latitude", "abbreviation": "Lat", "direction": "north", "unit": "degree" }, { "name": "Geodetic longitude", "abbreviation": "Lon", "direction": "east", "unit": "degree" } ] }, "id": { "authority": "EPSG", "code": 4269 }, "remarks": "Longitude is POSITIVE EAST. The adjustment included connections to Greenland and Mexico but the system was not adopted there. For applications with an accuracy of better than 1m replaced by NAD83(HARN) in the US and PRVI and by NAD83(CSRS) in Canada." }, "transformation": { "name": "NAD27 to NAD83 (7)", "method": { "name": "NADCON5 (2D)", "id": { "authority": "EPSG", "code": 1074 } }, "parameters": [ { "name": "Latitude difference file", "value": "nadcon5.nad27.nad83_1986.conus.lat.trn.20160901.b", "id": { "authority": "EPSG", "code": 8657 } }, { "name": "Longitude difference file", "value": "nadcon5.nad27.nad83_1986.conus.lon.trn.20160901.b", "id": { "authority": "EPSG", "code": 8658 } } ], "id": { "authority": "EPSG", "code": 8555 } } }
Definition: Mapnik
<?xml version="1.0" encoding="utf-8"?> <Map srs="+proj=lcc +lat_0=25.6666666666667 +lon_0=-91.3333333333333 +lat_1=27.8333333333333 +lat_2=26.1666666666667 +x_0=609601.219202438 +y_0=0 +datum=NAD27 +units=us-ft +no_defs +type=crs"> <Layer srs="+proj=lcc +lat_0=25.6666666666667 +lon_0=-91.3333333333333 +lat_1=27.8333333333333 +lat_2=26.1666666666667 +x_0=609601.219202438 +y_0=0 +datum=NAD27 +units=us-ft +no_defs +type=crs"> </Layer> </Map>
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