How to plot level curves

I have an equation Z = exp(-0.5.*((X-800)./40).^2).*cos(2*pi.*Y*1000./X).

I want to plot level curves of Y from -100 to 100 against X from 700 to 900 for Z = -1 to 1. The graph is supposed to look like the one below.

I have tried surf but it's ignoring the axis limits I set. I also don't know how to set Z to different values.

[X,Y] = meshgrid(700:1:900,-100:1:100);

Z = exp(-0.5.*((X-800)./40).^2)*cos(2*pi.*Y*1000./X);

surf(Z)

Any help is appreciated!