Identification Information

Title National Geodetic Survey (NGS) Geodetic Control Stations, (Horizontal and/or Vertical Control), March 2009

Date 2009-03-11

Date Type Publication

Cited Responsible Party

Organization Name NOAA, National Geodetic Survey

Role identify

Presentation Form vector digital data

Abstract This data contains a set of geodetic control stations maintained by the National Geodetic Survey. Each geodetic control station in this dataset has either a precise Latitude/Longitude used for horizontal control or a precise Orthometric Height used for vertical control, or both. The National Geodetic Survey (NGS) serves as the Nation's depository for geodetic data. The NGS distributes geodetic data worldwide to a variety of users. These geodetic data include the final results of geodetic surveys, software programs to format, compute, verify, and adjust original survey observations or to convert values from one geodetic datum to another, and publications that describe how to obtain and use Geodetic Data products and services.

Purpose Provide a base of reference for latitude, longitude and height throughout the United States.

Data Set Credit NOAA, National Geodetic Survey and cooperating organizations

Status Complete

Point of Contact

Individual Name Craig Larrimore

Organization Name

Position Name IT Specialist

Role Point of contact

Voice 301-713-3257x152

Facsimile 301-713-4172

Address

Delivery Point SSMC2/9152 1315 East-west Highway
City Silver Spring
Administrative Area MD
Postal Code 20910
Country USA

Electronic Mail Address Craig.Larrimore@noaa.gov

Maintenance and Update Frequency Continually

Descriptive Keywords NSRS, geodetic, horizontal control, vertical control, ellipsoid height, benchmark, orthometric height, latitude, longitude

Access Constraints Geodetic Data are in the public domain, not restricted from access or distribution.

Use Constraints Not restricted; Geodetic Data, including software were developed and compiled with U.S. Government funding; no proprietary rights may be attached to them nor may they be sold to the U.S. Government as part of any procurement of ADP products or services.

Language English

Topic Category location

Extent

Geographic Bounding Box

West Bound -109.056738
East Bound -103.002383
North Bound 37.0
South Bound 31.332258

Temporal Extent

DateTime 2009-02-12

Data Quality Information

Attribute Accuracy Report

Report Horizontal control stations (those with precise Latitude, Longitude) were established in accordance with FGDC publications "Standards and Specifications for Geodetic Accuracy Standards" and "Geometric Geodetic Accuracy Standards and Specifications for Using GPS Relative Positioning Techniques" The final Latitude, Longitude of these stations were determined by a least squares adjustments of the horizontal observations. Horizontal control station have Latitude, Longitudes displayed to 5 places and are identified by attribute POS_SRCE = 'ADJUSTED' Lesser quality Latitude, Longitudes may also be preset in the dataset. These are identified by a POS_SRCE attributes HD_HELD1, HD_HELD2, or SCALED. These lesser quality positions are described at: http://www.ngs.noaa.gov/cgi-bin/ds_lookup.prl?Item=SCALED Vertical control stations (those with precise Orthometric Heights) were established in accordance with FGDC publications "Standards and Specifications for Geodetic Accuracy Standards" The final Orthometric Height of these stations were in most cases determined by a least squares adjustments of the vertical observations but in some cases may have been keyed from old survey documents. Vertical control stations have Orthometric Heights displayed to 2 or 3 places and are identified by attribute ELEV_SRCE of ADJUSTED, ADJ UNCH, POSTED,READJUST,N HEIGHT,RESET,COMPUTED Lesser quality Orthometric Heights may also be preset in the dataset. These are identified by a ELEV_SRCE attributes GPS_OBS, VERT_ANG, H_LEVEL, VERTCON, SCALED. These lesser quality orthometric heights are described at: http://www.ngs.noaa.gov/cgi-bin/ds_lookup.prl?Item=SCALED IMPORTANT - Control stations do not always have both precise Latitude, Longitude AND precise Orthometric Height. A horizontal control station may have a orthometric height associated with it which is of non geodetic quality. These types of heights are displayed to 0, 1, or 2 decimal places. Worst case being off by +/- 1 meter. LIKEWISE - A Vertical control station may have a Latitude, Longitude associated with it which is of non geodetic quality. These types of Latitude, Longitudes are displayed to 0, 1 or 2 decimal places. Worst case being off by +/- 180 meter. Refer to http://www.ngs.noaa.gov/cgi-bin/ds_lookup.prl?Item=SCALED for a description of the various type of methods used in determining the Latitude, Longitude, and Orthometric Height. Attribute POS_CHECK and ELEV_CHECK indicate whether or not an observational check was made to the position and/or orthometric height. Care should be taken when using "No Check" coordinates. If attribute ELEV_SRCE = 'VERTCON' then the Orthometric Height was determined by applying NGS program VERTCON to an Old NGVD 29 height. In most areas VERTCON gives results to +/- 2 cm. See http://www.ngs.noaa.gov/TOOLS/Vertcon/vertcon.html for a more detailed explanation of VERTCON accuracy. Ellipsoid Heights are also present in the dataset. The ellipsoid heights consist of those determined using a precise geoid model, which are displayed to 2 decimal places and are considered good to +/- .005 meters, and those displayed to 1 decimal place and are considered only good to +/- .5 meters

Quantitative Attribute Accuracy Assessment

Attribute Accuracy Value 95 percent confidence level for geodetic quality data.
Attribute Accuracy Explanation Geodetic Data are continuously being processed; their standards and specifications are being reviewed for next publication release. "Standards and Specifications for Geodetic Control Networks", 1984 and "Geometric Geodetic Accuracy Standards and Specifications for Using GPS Relative Positioning Techniques," FGCS (formally FGCC) publication version 5.0 1989, are most current published documents.

Horizontal Positional Accuracy Report

Report The description of tests are explained in "Geometric Geodetic Accuracy Standards and Specifications For Using GPS Relative Positioning Techniques," FGCS (formally FGCC) publication version 5.0, 1989. .05 meters for highest order of accuracy.

Quantitative Horizontal Positional Accuracy Assessment

Horizontal Positional Accuracy Value .05
Horizontal Positional Accuracy Explanation Horizontal positional accuracy statements pertain to horizontal control stations only. i.e. Those with geodetic quality Latitude, Longitudes. Positional Accuracy explanation contained in "Geometric Geodetic Accuracy Standards and Specifications For Using GPS Relative Positioning Techniques," FGCS (formally FGCC) publication version 5.0, 1989, (See table 1, p6). with the exception of Order A and Order B which have an accuracy of as described at: http://www.ngs.noaa.gov/cgi-bin/ds_lookup.prl?Item=HORZ%20ORDER

Vertical Positional Accuracy Report

Report The description of tests are explained in "Geometric Geodetic Accuracy Standards and Specifications for Using GPS Relative Positioning Techniques," FGCS (formally FGCC) publication version 5.0, 1989, (See table 1, p6). .05 meters for highest order of accuracy

Quantitative Vertical Positional Accuracy Assessment

Vertical Positional Accuracy Value .05
Vertical Positional Accuracy Explanation Vertical positional accuracy statements pertain to vertical control stations only. i.e. Those with geodetic quality Orthometric Heights. Orthometric Height accuracy explanation is contained in FGDC publication "Standards and Specifications for Geodetic Control Networks" with the exception of vertical control of class 0 POSTED and READJUSTED Heights which are described at: http://www.ngs.noaa.gov/cgi-bin/ds_lookup.prl?Item=VERT%20ORDER Ellipsoid height accuracy explanation contained in "Geometric Geodetic Accuracy Standards and Specifications for Using GPS Relative Positioning Techniques," FGCS (formally FGCC) publication version 5.0, 1989. (see table 1, p6). The accuracies for ellipsoid heights are described at: http://www.ngs.noaa.gov/cgi-bin/ds_lookup.prl?Item=ELLP%20ORDER

Logical Consistency Report FGCS sponsored testing in cooperation with equipment manufacturers and National Institutes of Standards and Technology, Gaithersburg, MD 20850

Completeness Report This dataset DOES NOT include destroyed marks. All other non-publishable marks are NOT included. Non-publishable criteria is available at http://www.ngs.noaa.gov/cgi-bin/craigs_lib.prl?HELP_NONPUB=1

Lineage

Source Information

Source Citation

Source Scale Denominator

Type of Source Media paper, Web

Source Time Period of Content

DateTime 1994
Source Currentness Reference publication date

Source Citation Abbreviation Blue Book

Source Contribution The geodetic data must be submitted in the digital formats specified in the FGCS (formally FGCC) publication "Input Formats and Specifications of the National Geodetic Survey Data Base" which describes the formats and procedures for submission of data for adjustment and assimilation into the National Geodetic Survey Data Base. Separate volumes of this publication refer to horizontal (volume 1), vertical (volume 2), and gravity (volume 3) control, and are available from NOAA, National Geodetic Survey, 1315 East-West Hwy, Code N/CGS1, Silver Spring, MD, 20910 (1-301-713-3242). Note guidelines for submission of three-dimensional Global Positioning System (GPS) relative positioning data are contained in annex L to volume 1.

Process Step

Process Description The National Geodetic Survey produces geodetic data. Geodetic data comprise the results of geodetic surveys to determine, among other things, latitude, longitude, height, scale, and orientation control. The National Geodetic Survey original field survey project observations and final reports are accessioned into records system of the National Archives and Records Administration of the U.S.A. These surveys provide information valuable for a variety of uses in the mapping, charting and surveying community. The NGS' final product is the geodetic data sheet. Geodetic data sheets are comprehensive summaries of all published information for a given geodetic reference point, including: the geographic position and/or height based on the current reference datum, condition of the survey mark when it was last visited, a description of where the point is located and how to reach it, and an explanation of the terms used in the data sheet. In support of these geodetic data, the NGS provides software, publications, and various user services, including geodetic advisor program, instrument calibration, surveying standards, and technical workshops. This dataset contains certain information extracted from the above mentioned data sheet.

Source Used Citation Abbreviation Blue Book

Process Date Not complete

Process Time

Process Contact

Individual Name Craig Larrimore

Organization Name

Position Name IT Specialist

Role Point of contact

Voice 301-713-3257x152

Facsimile 301-713-4172

Address

Delivery Point SSMC2/9152 1315 East-west Highway
City Silver Spring
Administrative Area MD
Postal Code 20910
Country USA

Electronic Mail Address Craig.Larrimore@noaa.gov

National Geodetic Survey (NGS) Geodetic Control Stations, (Horizontal and/or Vertical Control), March 2009

Metadata from the RGIS Metadata Repository

Identification Information

Distribution Information

Spatial Reference Information

Data Quality Information

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