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Estimated AHD Positional Uncertainty. Derived from a recent homogeneous adjustment of the ANLN, constrained as in the 1971 AHD adjustment. Combines: Uncertainty in the 1971 adjustment: Difference between the published AHD and the height from the recent adjustment &
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Estimated AHD Positional Uncertainty • Derived from a recent homogeneous adjustment of the ANLN, constrained as in the 1971 AHD adjustment. • Combines: • Uncertainty in the 1971 adjustment: • Difference between the published AHD and the height from the recent adjustment & • Uncertainty due to the levelling propagation • Std Dev of the height from recent adjustment
Difference Between published AHD & recent adjustment Uncertainty of height in recent adjustment
Estimated AHD Positional Uncertainty • A few outliers to be resolved • Conforms with conventional wisdom of the originators of AHD: “accuracy of AHD in the centre of Australia is about a foot…” (1 foot ~ 30 cm)