The NII 2143 A doublet has been observed in the aurora with a rocket spectrometer. An altitude profile of the NII doublet has been obtained and compared with the profiles of the N2 Lyman-Birge-Hopfield (LBH) bands and N2+ 3914 A. At high altitudes the ratio of the NII 2143 A emission to LBH=0.022¿0.004, and the ratio of NII 2143 A to N2+ 3914 A=0.095¿0.04. From these ratios we find that the peak excitation cross section of N+(5S) equals 1-2¿10-18 cm2. At low altitudes the NII doublet is quenched by molecular nitrogen. The deduced value of the quenching coefficient equals 5.5¿10 -10 cm3 s-1. ¿American Geophysical Union 1987