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Control Point Survey : Outline


Control Point Survey

In the unique ice-covered environment that is Antarctica, control point surveys required taking independent astronomical surveys at each ice-free area to obtain latitudinal and longitudinal bearings. However, unconformities in the surveys between areas or in large scale maps were points of concern.
Therefore, we started integrating our geodetic networks in the 1960's. In the 1970's, we incorporated the use of electro-optical distance measurements(Geodimeter Model 8) that allowed accurate measurements over long distances and high-precision theodolites (Wild T3).
However, our integration work was restricted to the southern vicinity of the Syowa station as the distances between ice-free areas in other parts were too great for line of sight confirmation.
At the start of the 1990's, the advent of GNSS(GPS) facilitated continuous GNSS(GPS) observation and SCAR campaign surveys, accurately integrating the coordinates of the Syowa station into the global geodetic network
Currently, IGS station at Syowa station (SYOG) is being used as a control point survey origin for GNSS relative positioning, helping the effort to build a global geodetic network.
Control Point Survey

Survey Standard

The first survey standard used in the Antarctic region was GRS-67 which was in use for a long time for control point surveys and topographic mapping. GRS-67 is Earth ellipsoid which was adopted as the international geodetic reference system at the 14th meeting of the IUGG (International Union of Geodesy and Geophysics) held in 1967, and widely used until it was superceded by GRS-80 adopted at the 17th meeting of the IUGG held in 1980.
After the 25th meeting of SCAR in 1998, we changed to using the ITRF (International Terrestrial Reference Frame) as the geodetic reference system, based on the recommendation issued by the Working Group on Geodesy and Geographical Information.
In March 2001, the coordinates of IGS station (SYOG) for GNSS (GPS) continuous observation and VLBI observation station at Syowa station were incorporated into ITRF2000 realization, and registered with the IERS (International Earth Rotation and Reference System Service).
Coordinates of control points observed after the 33rd JARE (1991) has been recalculated based on ITRF2000 using IGS station at Syowa station (SYOG) as the fixed station, and using the GRS80 ellipsoid.
All coordinates of control points (including renewal and recalculation) provided by this service has been updated based on ITRF2000.

Geodetic Coordinate System

  1. Current geodetic reference system (GRS80 ellipsoid; ITRF2000)
    1. (1) GRS80 ellipsoidal parameters
      Equatorial radius a=6,378,137m Ellipticity f=1/298.257222101
    2. (2) Origin and datum
      Origin is taken as the reference point of the continuous GNSS (GPS) observation station at Syowa station.
      Datum expressed as ITRF2000 cubic coordinates.
      (ITRF2000 coordinates) (Longitude, latitude, and ellipsoidal height based on GRS80)
      X= 1,766,207.852m
      Y= 1,460,290.346m
      L= 39°35′01″.4784
      h= 50.003m
      Reference point of the observation station is taken as directly below the antenna phase center, at the point where the antenna is attached to the base.
      Note:Each meaning of the letters on the graph is as follows.
      • X: X coordinate (m)
      • Y: Y coordinate (m)
      • Z: Z coordinate (m)
      • B: latitude (degrees, minutes, seconds)
      • L: longitude (degrees, minutes, seconds)
      • h: ellipsoidal height (m)
      • H: elevation (m)
  2. Conventional geodetic reference system (GRS-67)
    1. (1) Ellipsoidal parameters
      Equatorial radius a=6,378,160m Ellipticity f=1/298.25
    2. (2) Parameters for converting WGS72 to GRS-67
      • DX=292.82 m (displacement on the X-axis)
      • DY=-227.49 m (displacement on the Y-axis)
      • DZ=29.93 m (displacement on the Z-axis)
      Scale correction and rotation are zero.
      Calculations based on astronomical point data and JMR data (WGS72) from Syowa station
      Astronomical point data JMR data
      L= 39°35′24″000
      H= 29.18
      L= 39°34′51″428
      H= 54.91
    3. (3) Parameters for converting WGS84 to WGS72
      • DX= 0.00 m (displacement on the X-axis)
      • DY= 0.00 m (displacement on the Y-axis)
      • DZ=-4.50 m (displacement on the Z-axis)
      • rx= 0.0000″(rotation on the X-axis)
      • ry= 0.0000″(rotation on the Y-axis)
      • rz=-0.5540″(rotation on the Z-axis)
      • S=-0.2263 ppm (scale correction)