Anomaly Selection for Deflection Interpolation Part 2. Practical Application

Abstract : The Test Phase utilized three astro-geodetic deflection stations in the Rocky Mountain area of the western United States. These were deflection stations 102, 105, and 116 from USC+GS Special Publication No. 229. Using the adopted procedure, the Xi deflection component was interpolated between stations 105 and 116 to obtain an interpolated Xi value at station 102. A comparison of this interpolated Xi value with the astro-geodetic Xi value showed that the two differed by only .22 in. Since the accuracy of the astrogeodetic values probably do not exceed =.2 in., the results were considered highly satisfactory. The Application Phase pursued deflection interpolation in an area in the Alps chosen by ACIC. In this case three deflection stations were chosen from a deflection of the vertical map provided by ACIC. These were designated stations 1, 2, and 3 for convenience. Using the adopted procedure, the eta deflection component was interpolated between stations 1 and 3 to obtain a value at station 2. As there were no individual deflection values given, the astro-geodetic deflections were estimated from a eta deflection component contour map with a 2.50 in. contour interval. Because of the manner of obtaining the astro-geodetic deflections, they are considered to have an accuracy of the order of =.5 in.