ATP-3-09-02 Field Artillery Survey Download
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Survey Methods 16 February 2016 ATP 3-09.02 7-5 based on the time of the observation. The problem of determining azimuth consists of taking a horizontal reading at the observer's station between the mark and sun, the azimuth of which can be computed. The simple operation of subtracting this horizontal angle from the computed azimuth of the sun gives the desired azimuth to the mark. Artillery Astronomic Observation Using a Star 7-20. The artillery astronomic method can be used with observations on Polaris or on east-west stars. Used with Polaris, this method yields the most accurate azimuths. When the artillery astronomic method is used with east-west stars, the requirement for accurate time is a disadvantage, but the method can be used when no stars meet the position requirements for the altitude method. Computation of artillery astronomic star is the same as the computations for artillery astronomic sun. The only differences are steps 9 and 9a of the form. Step 9 will be answered N (no). Step 9a asks for the star number which can be found on the reverse of the computation form. Procedures for Performing an Artillery Astronomic Observation 7-21. The instrument operator sets up his instrument as prescribed in Chapter 3. With the instrument telescope in the direct position, he points the telescope at the azimuth mark. After the initial circle setting has been recorded in the recorder's book, the instrument operator and recorder perform these steps: The instrument operator places the sun filter on the telescope and turns the instrument until the sun is near the center of the solar circle. He announces TRACKING. On the instrument operator's announcement of TRACKING, the recorder begins keeping time without lifting his eyes from the GPS or watch. At the instrument operator's announcement of TIP, the recorder notes the exact uncorrected and records it in the field notebook. The instrument operator reads the horizontal circle reading and announces it to the recorder. The instrument operator and recorder repeat steps 6, 7, and 8 two more times. Once 3 horizontal angles have been measured the instrument operator will plunge the scope and close out on the rear station (Azimuth mark). SIMULTANEOUS OBSERVATIONS 7-22. Simultaneous observations of a celestial body provide a quick method of transmitting direction over great distances without time-consuming computations. This method is ideally suited to the needs of the artillery since many units can be placed on common directional control in a very short period of time. Because of the great distance of celestial bodies from the earth, the azimuths to a celestial body at any instant from two or more close points on the earth are approximately parallel. The difference in the azimuth is caused by the fact that the azimuths at different points are measured with respect to different horizontal planes. PROCEDURES FOR SIMULTANEOUS OBSERVATIONS 7-23. Flank stations are established at points where azimuth is required. A master station is established at a point from which the grid azimuth to an azimuth mark is known or has been computed (see figure 7-2 on page 7-6), an assumed azimuth may be used. Both the flank and master stations should be points that are easily identified on a map and provide the best possible communications.