
JOURNAL OF RESEARCH IN NATIONAL DEVELOPMENT VOLUME 5 NO 1, JUNE, 2007
ERROR ANALYSIS OF CLOCK TIME (T), DECLINATION (*) AND LATITUDE (Φ) ON ASTRONOMIC AZIMUTH IN MINNA, USING SUN ALTITUDE AND HOUR ANGLE METHODS
M.L. OJIGI
DEPARTMENT OF SURVEYING & GEOINFORMATICS, FEDERAL UNIVERSITY OF TECHNOLOGY, MINNA – NIGERIA
ABSTRACT
The major end results of field and geodetic astronomy in surveying include time (t), latitude (Φ), longitude (λ) and azimuth (A); which are aimed at establishing fixed positions and orientations of survey points and lines on the earth surface. The paper attempts the analysis of the individual and combined effects of error in time (t), declination (δ) and latitude (Φ) on the computed azimuths (A) using the methods of altitude and hour angle of the sun, in Minna. The actual mean azimuth of the baseline (LS2K1 – P2) in a classical field observation procedure in both methods were 344° 32’ 29.1” and 344° 32’ 29.7” respectively. Deliberate observation and interpolation errors in the three parameters (t, δ and Φ) were made in order to evaluate their individual and combined effects on the azimuth determinations respectively. In the sun altitude method, it was discovered that timing error of 10 min resulted in 7.6” error in the interpolation of declination, which in turn yielded error of about 9.9” in the computed azimuth (A). Also, declination interpolation of declination, which in turn yielded error of about 13” in the computed azimuth, and error of 10” in the scaled latitude resulted in error of 5.2” in the computed azimuth. Therefore, the combined error effects of 10” error in declination and latitude respectively (dA) on the computed azimuth was about 18.2”. In the hour angle method, it was observed that error in timing of about 56 seconds caused error in the computed azimuth of up to 53” of arc. An error of 6” in declination caused error of 3” in the computed azimuth, while error of 5” in latitude caused corresponding error of about 3” in the computed azimuth. Time is therefore a major factor in hour angle method despite the fact that it is not directly used in the equation for the azimuth computation. The multiple regression analysis of the variables shows a positive statistical significance of 99.8% in the relationship between dependent variable (A) and independent variables (t, δ and Φ). It is recommended that to avoid unnecessary errors prior and post astronomical survey and analysis, sincerity of purpose and data integrity must be ensured.
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