A new least-squares method for the circle using a set of coordinate da
ta (x(i), y(i)) is presented. This method provides analytical expressi
ons for the coordinates ((X) over cap(0), (Y) over cap(0)) of the cent
ral point of a circle and its radius (R) over cap(0). Expressions for
the variances V((X) over cap)(0), V((Y) over cap)(0) and V((R) over ca
p(0)), and the covariances cov((X) over cap(0), (Y) over cap(0)), cov(
(X) over cap(0), (R) over cap(0)) and cov((Y) over cap(0)(R) over cap(
0)) are also presented. The method is applied to two problems, one in
interferometry and the other in radiometry.