Jobsite Azimuths Made Easy with Mica

Abstract

Finding the direction of a line is done simply and accurately with a multiyear interactive computerized almanac (Mica), a theodolite, and a hand-held programmable calculator. Mica is the Multiyear Interactive Computer Almanac that is available from the U.S. Naval Observatory. An astronomic azimuth from station 081 to station 080 is measured with a set of six solar observations and the resulting average azimuth is compared to the value established by the Vermont Agency of Transportation (VAT), using the global positioning system. Each of the six sun shots is made by an independent observer, who in this study is represented by a first-year civil engineering student. Three readings were done with the telescope reversed and three were taken with the telescope direct. The local hour angle (LHA) method is used to calculate the astronomic azimuth. The solar constants for the equation of time (EOT), for declination (δ), and for semidiameter (SD) are found in Mica. The astronomic Azimuth 081–080 is 235° 15′ 50″ from the student readings and is 235° 15′ 56″ from VAT data.