Effective recombination coefficientsErrors in the computed effective recombination coefficients for nebular N ii lines in an earlier publication (Fang et al. 2011) have been discovered and are here corrected. Those errors were not due to the basic atomic physics (i.e. creation of the N 2+ target and the target wave functions, and calculations of bound-state energies, oscillator strengths and photoionization cross-sections for the N ii states) but due to mislabeling of five N ii bound-state energy levels. o 2 levels were swapped. As a consequence, the effective recombination coefficients for the N ii lines that are directly related to the above five states were incorrect. We have corrected the labeling of the N ii energy levels and re-calculated the effective recombination coefficients for the N ii lines at the same electron temperature and density ranges as in Fang et al. (2011). The newly calculated effective recombination coefficients are given in Tables 3-6. Effective recombination coefficient fitsAnalytical fits to the effective recombination coefficients as a function of electron temperature were carried out for the 55 strongest transitions of N ii in the optical (Tables 7-14 in Fang et al. 2011), using a non-linear least-squares algorithm. Two temperature regimes were defined, the low-temperature regime (T e < 10 000 K) and the high-temperature regime (10 000 ≤ T e ≤ 20 000 K), and different fit equations were used for the two regimes (Eqs. (3) and (4) (Eq. (4)) was not ideal. In the current corrigendum, we present new analytical fits for the 55 lines of N ii, using the single equation, valid for 125 K ≤ T e ≤ 20 000 K, α = a + b t + c t 2 + (d + e t + f t 2 ) log 10 t + g (log 10 t)where α = log 10 α eff + 15 and t = T e [K]/10 4 , and α eff is the effective recombination coefficient of an N ii line as defined by

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