*APPENDIX E
ELLIPSOIDS AND DATUMS
The PADS Core (Version 8), PADS Solid State (Version 4), BUCS Survey (Rev 1), BUCS DDCT (Rev 0), MADTRAN (Edition 2), MADTRAN (Edition 4), PLGR (Version 04.62), and FED MSR systems contain a data base that stores the relevant constants and parameters for the ellipsoids listed in Table E2.
E1. REFERENCES
a. The following references were used to compile the information found in this appendix:
(1) DMA TM 8358.1 (September 1990).
(2) DMA TR 8350.2 Second Edition (1 September 1991) with Insert 1 (9 December 1993).
(3) National Geodetic Survey, Geodetic Glossary (September 1986).
(4) DoD Glossary of Mapping, Charting, and Geodetic Terms (1991).
(5) MADTRAN, Edition 2 and 4 (DMA program referencing DMA TR 8350.2 above).
(6) Mercator (DMA program referencing DMA TM 8358.2 (dated September 1989).
(7) TM 08837A12/1A (28 October 1988) with Change 3 (9 September 1992) PADS.
b. When the information in the references above conflicted, DMA TR 8350.2 was considered the senior publication.
c. The numbers in front of the references above correspond to the reference numbers in the tables of this appendix. Reference 8 was used to determine the PADS ellipsoid code; Reference 4 was used to determine the BUCS DDCT (Rev 0) code.
E2. TABLES
(1) Table E1 is a list of all ellipsoids and their parameters as published in the references above.
(a) This is not a list of all ellipsoids; however, it is the most complete onetable list of ellipsoids and their parameters available to artillery surveyors.
(b) The semimajor axis (a), semiminor axis (b), and flattening (1/f) are listed when available. Semiminor axes not listed were not available from the references and must be computed by the user with the formula b = a (1  f).
(2) Table E2 is a list of the ellipsoids in Table E1 crossreferenced with current survey applications.
b. Datums.
(1) The datum transformation parameters are listed corresponding to the ellipsoid to which they are referenced. The transformation parameters are from the local geodetic datum to WGS84; therefore, a datum table with WGS84 will not be published. Also, datum tables for ellipsoids in Table E1 with no listed datums are not published.
(2) Differences in data published in the above references are explained in the notes section at the end of this appendix.
E3. WORLD GEODETIC SYSTEM
a. Because of the large amount of mapping, charting, geodetic, gravimetric, and digital products produced by DMA for DoD, it became apparent that a single geocentric coordinate system was needed to ensure accuracy and user interface. This system must support the widest range of applications. A geocentric system provides a basic reference for the mathematical figure of the earth. It also provides a means for establishing various geodetic datums to an earthcentered, earthfixed (ECEF) coordinate system. This system is termed World Geodetic System (WGS).
b. Previously, DoD has adopted three such systems: WGS60, WGS66, and WGS72. With each system proving more accurate than the last, WGS72 can still be used for some applications. It does, however, have several shortcomings. For example, the WGS72 Earth Gravitational Model and Geoid are obsolete. Also, more accurate datum shifts from local geodetic datums to a WGS were needed. Several other factors contributed to the need to replace WGS72. These included the replacement of NAD 27 with NAD 83 and the development of the Australian Geodetic Datum 84. Also, a large increase in data and more advanced types of data (satellite ranging for example) were now available. WGS84 was developed as the replacement for WGS72.
c. In determining the WGS84 ellipsoid and its associated parameters, the WGS84 Development Committee closely followed the procedures used by the International Union of Geodesy and Geophysics (IUGG) who had already developed the Geodetic Reference System 1980 (GRS80). Four parameters were used to develop WGS84: the semimajor axis (a), the earth's gravitational constant (GM), the normalized second degree zonal gravitational constant (), and the angular velocity () of the earth. All are identical to GRS80 except that the second degree zonal used is that of the WGS84 gravitational model instead of the notation J_{2} used for GRS80. As a result of that difference, the ellipsoid parameters differ slightly between GRS80 and WGS84. These differences are insignificant from a practical application standpoint; therefore, it has been accepted that GRS80 and WGS84 are the same and their associated datums are based on the same ellipsoid. Even so, it must be understood that WGS84 is datum within the WGS84 ellipsoid, and NAD83 is a datum referenced to the GRS80 ellipsoid.
d. DMA has designated WGS84 as the preferred ellipsoid and datum for all mapping, charting, and geodetic products. Some areas of the world can still be covered by other systems.
E4. DATUM TRANSFORMATION TABLES
a. A datum transformation table (Figure E2) includes the following information:
 Ellipsoid name, semimajor axis (a), semiminor axis (b), and flattening (1/f) as listed in Table E1.
 , which is the difference between the semimajor axes of the local reference ellipsoid and WGS84.
 10^{7}, which is the difference between the flattenings of the local reference ellipsoid and WGS84 multiplied by 10^{7}.
Note. Both and x 10^{7} are necessary for the userdefined option in the AN/PSN11 (PLGR) Version V04b.2. 
 PADS code as listed in TM 08837A12/1A. In cases where two or more ellipsoids have the same parameters, the same PADS code was listed for each even when not listed in the reference. For example, Australian National and South American 1969 can both use code 8. These codes are for Version 4 PADS. If a PADS code is not listed, the userdefined option should be used.
 Local geodetic datum. The datum name as it appears in DMA TR 8350.2. In cases where a datum has more than one name, the second name is listed in parentheses.
 Country/area. This information is mostly as it appears in DMA TR 8350.2. The only variations from the reference are listings of states and countries published under mean solutions.
 Transformation parameters (shifts in X, Y, and Z axes) as listed in DMA TR 8350.2. These parameters are from the local datum to WGS84.
 Datum code. The codes in the DATUM CODE column match the programmed datum codes from the AN/PSN11 (PLGR) Version V04b.2. The datum codes listed in this column that are not a programmed option of the PLGR must be selected as userdefined. All datum codes published in this table are from DMA TR 8350.2.
 DDCT code. This is the datum code from the BUCS DDCT Rev 0.
b. Tables E3 through E25 are datum transformation tables. A quick reference to the location of specific tables is located above.
E5. NOTES FOR DATUM TABLES
a. Note 1. Any entry reading SEE NOTE ONE in Tables E3 through E25 of this appendix are so noted because of inconsistent listings of datums referenced to the Clarke 1880 ellipsoid. Table E1 lists five different Clarke 1880 ellipsoids. DMA has adopted only one. Different countries have adopted different dimensions for the Clarke 1880 ellipsoid. These differences depend on two things: which of Clarke's original numbers were used ([a, b] or [a, f]) or which foottometer conversion was used.
(1) In areas referenced to the ARC 1950 datum, the Clarke 1880 dimensions adopted are shown below.
a: 6378249.145326 b: 6356514.966721 f: 1/293.4663076
(2) In areas referenced to Carthage, Merchich, and Voirol datums, the adopted dimensions are shown below.
a: 6378249.2 b: 6356515.0 f: 1/293.46598
(3) The DMAadopted dimensions are shown below.
a: 6378249.145 b: 6356514.8696 f: 1/293.465
(4) DMA TM 8350.2 with Insert 1 lists datum transformation parameters for local datums referenced to the DMAadopted Clarke 1880 and not the dimensions adopted by other countries. Any datum with SEE NOTE ONE in the DDCT CODE column should be transformed to other datums with the userdefined option.
b. Note 2. WGS72 is transformed to WGS84 with a formula that is more accurate than the Abridged Molodensky formulas; therefore, datum shifts are not necessary. The formulas used are as follows:
These formulas are explained in detail in DMA TR 8350.2.
c. Note 3. Herat North Datum was used by the Soviet Union with Krassovsky as the reference ellipsoid in northern Afghanistan. The US and United Kingdom used Herat North Datum with International as the reference ellipsoid to triangulate in southern Afghanistan. The connection between these two systems usually differs by 20 to 30 meters. Herat North Datum referenced to Krassovsky ellipsoid is programmed option in the GaussKruger Grid (Module 15) in the BUCS DDCT Rev 0.
d. Note 4. Potsdam Datum was used with the GaussKruger Grid in eastern Germany and is a programmed option in Module 15 of the BUCS DDCT Rev 0.
e. Note 5. The IUGG recommended the adoption of the ellipsoid GRS67 at their 1967 meeting in Lucerne, Switzerland. The new ellipsoid was adopted for use when a greater degree of accuracy was needed than could be obtained with the International 1924 ellipsoid. The ellipsoid became part of the Geodetic Reference System of 1967, which was adopted in 1971 by the IUGG meeting in Moscow. This ellipsoid is used in both South America and Australia; however, the name was changed to South American 1969 and Australian National to more conveniently describe the reference ellipsoid. DMA TR 8350.2 lists the more convenient names of these ellipsoids.
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