  The method of isolines (contours) is proposed to be used for deter- mination
of core location of extensive air shower on the array plane. As variable
z=f(x,y) are used flux densities of particles, registrated from ground
detectors. Obtained isolines are approximated with circles, which centers show
impact point of shower axis. The method was demostrated on experimental data
from Tien-Shan shower array in period 1974-82. The possibilities and
difficulties of the method are discussed.
