ATP-3-09-02 Field Artillery Survey Download
Page 102 of 168
Chapter 7 7-14 ATP 3-09.02 16 February 2016 Figure 7-9. Celestial body final azimuth error 1 Figure 7-10. Celestial body final azimuth error 2 7-36. Low star rates are not essential for astronomic observations, because altitude is not measured. However, stars with low star rates will be moving more slowly in azimuth and will be easier to track than those with high star rates. Although Polaris has a high star rate in its culminations, its apparent motion is so slow that it can be observed successfully at any time. Avoid observing stars below 175 mils in altitude because of possible errors caused by refraction. WORLD STAR CHART 7-37. A map depicts the prominent points on the earth, and the star chart depicts the prominent points in the sky (see figure 7-11 on page 7-15). On the earth latitude and longitude are used to fix the location of points; declination and right ascension are generally used to fix the stars at definite coordinates. Consequently, on a star chart the north-south location of a star is fixed by declination, and the east-west location is fixed by right ascension.