ATP-3-09-02 Field Artillery Survey Download
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Chapter 7 7-12 ATP 3-09.02 16 February 2016 Figure 7-7. Star finder and identifier Haught (Field-Expedient) Method for Orienting the Star Identifier 7-34. This is a simple method of computing the local sidereal time (LST) for orienting the star finder and identifier. The results are accurate to within 1° and can be used for any time or location. The final result is the LST for 1900 on the date of observation. Use the time-arc relationship to adjust for different observation times. One hour is equal to 15° of shift on the star finder and identifier, and 4 minutes is equal to 1° of shift. To compute the LST by using the Haught method, follow these procedures: Count the number of months this year proceeding the observation month. Multiply that number by 30. Add the observation date. Add a constant of 24. Determine the difference between the observer's longitude and the longitude of the central meridian of the observer's time zone. Add the difference if the observer is east; subtract if west. If using daylight saving time, subtract 15. Daylight saving time in the US is currently from the second Sunday in March to the first Sunday in November. The result is the LST (orienting angle) to set on the star identifier for 1900.