Sky distribution of G21 10 mag < Ks < 16.2 mag galaxy candidates (blue triangles) and extended sources identified in this work within tile b204 (red dots). On the right-hand side of the figure, we show one example of a G21 galaxy that matches our extended source list (top), an extended source that has not been identified in G21 (middle), and a G21 galaxy that does not fulfill our extended selection criteria (bottom), respectively. The images are 1 arcmin × 1 arcmin.