Left: location of the sample carbon stars of different spectral types on the Galactic plane. The Sun is placed at (X, Y) = (0, 0). Stars shown are N-type (blue); J-type (red); SC-type (green), and R-hot type (brown). Right: distribution above or below the Galactic plane vs. the Galactocentric distance. The Sun is at R = 8.34 kpc. The typical uncertainty in the (X, Y, Z) coordinates is ±20 pc, and ±50 pc for the Galactocentric distance. Two N-type stars with peculiar locations above the Galactic plane are labelled (see text).