For accurate work, Cartesian (XYZ) coordinates are much to be preferred, since the use of latitude, longitude and height entails a number of possible uncertainties and ambiguities. In particular, there are two families of commonlyused geodetic coordinate systems (lat/long/height) that can differ by as much as 200m. (The fact that the ATCA site survey in 1984 fell into just this trap emphasises the point.)
The choice of the correct type of geodetic coordinate depends on the application. In most cases, the geocentric WGS84 given below will probably be appropriate (eg in the calculation of LST). The nongeocentric system AGD84/AHD currently used by Australian cartographers and surveyors is unlikely to be relevant for astronomy, but is included for completeness and to allow comparison with existing physical surveys.
Ref  X(m)  e(X)  Y(m)  e(Y)  Z(m)  e(Z) 

W196  4750915.837  ∼2  2792906.182  ∼2  3200483.747  ∼2 
W196_vlbi  4750924.9  ∼2  2792911.5  ∼2  3200489.9  ∼2 
MOPRA  4682768.1  ∼1  2802618.8  ∼1  3291759.2  ∼2 
PARKES  4554231.533  .031  2816759.109  .018  3454036.323  .025 
Notes: The coordinates are in a conventional geocentric righthanded Cartesian system, with the Z axis parallel to the mean rotation axis (North) and the Xaxis aligned towards the intersection of the Greenwich meridian and the equator.
W196 refers to the centroid of the four piertops of station W196 of the ATCA. The listed position is that currently in use by CAOBS in the STATION.COORDINATES file. The position is derived from a physical survey (preGPS: see ATNF documents AT/15.6.1/001003, AT/15.6.2/012) and is uncertain at the ∼2m level although the relative positions of the CA stations are accurate at the ∼mm level. The reference frame of the survey is unstated, but is probably AGD66. However, for consistency with existing coordinates in use at the ATCA it is assumed to be AGD84 (∼2m differences against AGD66). The geoidal height used in the survey (N[ANS]=11.4m) has also been retained for consistency (though more accurate estimates are since available).
The antenna coordinates used by CAOBS for array pointing prior to October 1991 were all approximately 200m in error (mostly a uniform translation) owing to a misconception of references systems in the surveyors' report. The coordinates currently in use are consistent with the position given here for W196.
Station W196 is the logical choice to define a single position for the entire array. It is exactly midway between the two outer stations (W0 and W392) and is the only station for which the four support piers lie in the true local horizontal plane to make the antenna azimuth axis strictly vertical. It should therefore be used to define local sidereal time (LST) for the whole array so that all antenna azimuth and elevation angles are consistent. (The azimuth axes of antennas on the other stations are all parallel to that of station W196 and are therefore progressively tilted from the vertical.)
W196_vlbi refers to a point 10 metres above the centroid of the pier tops, approximating the position of the intersection of the elevation and azimuth axes (relevant for VLBI). A more accurate estimate of the geoidal height has also been used (N[ANS]=13.5m or N[WGS84]=29.7m, based on OSU86E). This position will be improved by further VLBI observations (once an Hmaser is available).
The MOPRA and Parkes positions both derive from VLBI measurements and hence refer in both instances to the point of axial intersection. The Parkes position was obtained from S/X MarkIII VLBI data in January 1992 (ParkesHobartDSS45) and is nominally on the ITRF frame. The Mopra position was derived from 4.8 GHz MarkII data from May 1993.
Ref  Longitude  Latitude  Spheroidal 

(degs/dms)  (degs/dms)  Height (WGS84)  
W196  149.5501388  30.3128846  236.87m 
149 33 00.500  30 18 46.385  
MOPRA  149.0996405  31.2678132  866.44m 
149 05 58.706  31 16 04.127  
PARKES  148.2635101  32.9984064  414.80m 
148 15 48.636  32 59 54.263 
Notes: these figures are derived from the preceding Cartesian coordinates using the WGS84 figure for the Earth. This is close to the frame often used by GPS but note that some GPS receivers display position data in local coordinate systems (eg AGD84/ANS).
Ref  Longitude  Latitude  AHD height 

(degs/dms)  (degs/dms)  (above sea level)  
W196  149.5489798  30.3144576  209.30m 
149 32 56.327  30 18 52.048  
MOPRA  149.0984643  31.2693808  837.94m 
149 05 54.472  31 16 09.771  
PARKES  148.2623007  32.9999629  391.52m 
148 15 44.283  32 59 59.866 
Notes: The figures are derived from geocentric Cartesian coordinates using the Higgins (1987) sevenparameter transformation of WGS84 to AGD84. The latter is a coordinate system specific to Australia, using a nongeocentric spheroidal fit to the local geoid (the ANS, or Australian National Spheroid). The AHD height is height above mean sealevel or (equivalently) height above the geoid. For Narrabri, the AHD is that quoted in the surveyors' report (AT/15.6.1/003, AT/15.6.2/012). For Parkes and Mopra, values of N[WGS84] (height of the geoid above the WGS84 spheroid) are were interpolated on AUSGEOID93 (from OSU91).
Latitudes and longitudes read from Australian topographic maps are invariably in the above system or a precursor (eg AGD66). Some GPS receivers also allow positional data to be displayed in this system.
The names of Station Posts on the EastWest track are generated from their distance, in multiples of 15.306 metres, from the eastern most station post on the Compact Array (W0). Similarly, the names of station posts on the North Spur are generated from their increment from the southernmost station post on the north spur (W106).
Station  d (m)  Old name 

W0  0.000  (Station 1) 
W2  30.612  (Station 2) 
W4  61.224  (Station 3) 
W6  91.837  (Station 4) 
W8  122.449  (Station 5) 
W10  153.061  (Station 6) 
W12  183.673  (Station 7) 
W14  214.286  (Station 8) 
W16  244.898  (Station 9) 
W32  489.796  (Station 10) 
W45  688.776  (Station 11) 
W64  979.592  (Station 12) 
W84  1285.714  (Station 13) 
W98  1500.000  (Station 14) 
W100  1530.612  (Station 15) 
W102  1561.224  (Station 16) 
W104  1591.837  
W106  1622.449  
W109  1668.367  (Station 17) 
W110  1683.673  (Station 18) 
W111  1698.980  (Station 19) 
W112  1714.286  (Station 20) 
W113  1729.592  (Station 21) 
W124  1897.959  
W125  1913.265  
W128  1959.184  (Station 22) 
W129  1974.490  (Station 23) 
W140  2142.857  (Station 24) 
W147  2250.000  (Station 25) 
W148  2265.306  (Station 26) 
W163  2494.898  (Station 27) 
W168  2571.429  (Station 28) 
W172  2632.653  (Station 29) 
W173  2647.959  (Station 30) 
W182  2785.714  (Station 31) 
W189  2892.857  (Station 32) 
W190  2908.163  (Station 33) 
W195  2984.694  (Station 34) 
W196  3000.000  (Station 35) 
W392  6000.000  (Station 37) 
N2  30.612  
N5  76.531  
N7  107.143  
N11  168.367  
N14  214.286 
Notes:

Antennas 1 to 5 are confined to stations W0 to W196 and N spur stations. Antenna 6 is permanently stationed on station W392. Antennas must be separated by ≥30 m.

d is the distance in metres from W0 at the eastern end of the array, or, for N stations, the distance from the EW track.

Old names were used before 2002.