ATP-3-09-02 Field Artillery Survey Download
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Survey Methods 16 February 2016 ATP 3-09.02 7-3 Figure 7-1. Measuring horizontal and vertical angled from azimuth mark to celestial body 7-12. In all astronomic observations, the instrument must be perfectly level with reference to the most sensitive bubble the instrument has. An appreciable error, which cannot be eliminated by direct and reverse pointing, is introduced into the measurement of a horizontal angle between two objects of considerable difference in elevation if the vertical axis of the instrument is not vertical. Field Data Requirements 7-13. The field data requirements for survey are listed below: UTM coordinates (easting and northing) map-spotted to within 150 meters. Horizontal reading from the desired azimuth mark to the celestial body. Approximate azimuth to the desired azimuth mark. A magnetic or map-spotted azimuth will suffice. Date of observation. Time of observation. Sun (accurate to 1 second). Star (accurate to 1 second). Polaris (accurate to 10 seconds). Special requirements are: The sun should not be observed within 1 hour local apparent time of the observer's meridian. This is because there is no valid solution when angle t is less than 15° (1 hour). For best results, stars should be below 800 mils in altitude. Note. The restriction has been placed on vertical angles over 800 mils because of the error introduced into the horizontal angle measurement when the instrument has not been leveled perfectly. The error in the horizontal angle is equal to the tangent of the altitude of the celestial body multiplied by the error in leveling the plate of the instrument. Time Requirements 7-14. The primary means for achieving a correct time should be a GPS or DAGR device with a current crypto key loaded and a time figure of merit of 3. However; any good watch with a sweep second hand is