Point of Beginning

Answers: May 18

May 26, 2009

Problem: Surveying Astronomy Problems: Astronomical Coordinate Systems

The spherical triangle known as the PZS triangle has sides that are segments of three great circles. Which two of those great circles intersect at the star?

A. the prime vertical and the celestial equator
B. the hour circle and the horizon
C. the equinoctial colure and the celestial equator
D. the hour circle and the vertical circle

Solution: The acronym PZS stands for three points on the celestial sphere: the pole, the zenith, and the star. Each pair of points is included in a great circle. The great circle through the pole and the star is known as the hour circle. The great circle through the zenith and the start is known as the vertical circle. The great circle through the pole and the zenith is known as the observer's meridian.

The answer is (D).

This is problem 1(4-1) from the NEW third edition of “Surveying Solved Problems for the FS and PS Exams” by Jan Van Sickle, PLS (formerly "1001 Solved Surveying Fundamentals Problems"). Reprinted with permission from “Surveying Solved Problems for the FS and PS Exams” by Jan Van Sickle, PLS (2008 Professional Publications Inc.). For details on this and other FLS exam-prep books, call 800/426-1178 or visit www.ppi2pass.com.

> Click here for last week's question and solution