Last updated March 11, 2009
Navajo Nation Coordinate System Definition
Final Navajo Nation Coordinate System (NNCS) projection parameters were defined in October, 2007.
The NNCS was designed such that linear distortion is minimized at the topographic surface of the Earth
within the main coterminous part of the Navajo Nation. The centroid of this area was also used for the
NNCS central meridian, which minimizes convergence angles for the coterminous part of the Nation.
The coordinate system definition provides positive coordinates for all outlying areas, including Big
Boquillas Ranch, and coordinate values are less than one million meters everywhere on the Nation. In
addition, although the NNCS was designed for the coterminous part of the Nation, linear distortion has
been effectively minimized for the entire Nation. However, it should be noted that fairly large distortion
values still occur due to the very extensive coverage area and large topographic relief.
The defining parameters of the NNCS are provided below.
Linear unit: Meter
Geodetic datum (geometric reference frame): North American Datum of 1983 (2007 or 1992)
Note: The 2007 realization (“datum tag”) is the National Spatial Reference System of 2007
(NSRS2007) realization based on the NGS National Re-Adjustment of 2007 (NRA2007). The 1992
realization is also known as the High Accuracy Reference Network (HARN) realization. For the
purpose of reprojecting data using ESRI software, HARN can be considered equivalent to the 2007
realization.
For the area covered by the NNCS, NAD 83 (2007) can also be considered essentially equivalent to
NAD 83 (CORS96) at epoch 2002.00, to within about 1 cm. This is the current realization of the
NGS Continuously Operating Reference Station (CORS) network.
Despite the foregoing statements regarding “equivalence” between the various realizations of NAD
83, it is important that the actual realization used for the data be documented in the metadata to
ensure spatial consistency, particularly for high-accuracy (survey-grade) data. The information
provided here is current as of the document date. However, users of spatial data should be aware
that datum definitions (and naming conventions) vary greatly between different commercial software
packages, and that these definitions may change over time.
Projection type: Lambert Conformal Conic (single parallel)
Latitude of grid origin and standard parallel:
36° 00’ 00” N
= +36.000 000 000°
Longitude of central meridian:
109° 30’ 00” W = −109.500 000 000°
False northing (at grid origin):
300,000.000 m
False easting (on central meridian):
600,000.000 m
Scale factor on standard parallel:
1.00023 (exact)
Coordinate system design and documentation prepared by:
Geodetic Analysis, LLC
Michael L. Dennis, RLS, PE
8775 S Cluff Ranch Road
mld@geodeticanalysis.com
Pima, Arizona 85543
Phone: 928-322-0956
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NNCS definition_03-11-2009.docx