In the present work we have studied the rotational intensity distribution in the 0 – 0, 0 –1 and 1–3 bands of the B³
∏g–A³Σ⁺_u system of N₂ recorded on a Fourier transform spectrometer .The effective Hamiltonian used by Roux et al. (J .Mol. Spectrosc. 97 (1983) 253) for reduction of the experimental line position data to molecular parameters, is found to be adequate in reproducing the observed line intensities .To enhance the accuracy of the theoretical line intensity calculations, it proved necessary to use rotation-dependent Frank–Condon factor .Using the calculated intensities, it was possible to identify certain rotational lines belonging to the weakest branches Q₁₃ and Q₃₁, not reported before.