Upper panel: [O III] light curves from the outer rings of SN 1987A. The points correspond to both the λλ4959, 5007 Å lines. Middle panel: Hα light curves from the outer rings of SN1987A. Lower panel: [N II] light curves from the outer rings of SN 1987A. The points correspond to the λλ6548, 6583 Å line doublet. In all three panels the light curves from the southern outer ring are shown (area 4) on the left side, while on the right panels the light curves from the northern ring (area 1) are shown. Times are corrected for light travel time (see text).