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NGS Uses Astronomical Observations to Measure Gravity Deflections

Friday July 31, 2020

Using astronomical data, NGS is taking its first deflection of the vertical (DoV) measurements in 30 years. The DoV of a point on Earth is a measure of how far the direction of gravity has shifted because of local anomalies, such as nearby mountains. NGS's Geosciences Research Division is developing an autonomous system that captures video of selected stars to measure their precise angle above the horizon and estimate the DoV. Measuring DoV helps NGS model surface elevations and orient local coordinates to the global geospatial framework. This is another way to verify and maintain NGS's geometric and geopotential reference points. Accurate DoV measurements will also support precise geodetic infrastructure by orienting local surveys to a global geometric reference system.

For more information, contact: Ryan Hardy