Three new bands of the B2Σ+-X2Σ+ system of 12C17O+ have been investigated using conventional spectroscopic techniques. The spectra were observed in a graphite hollow-cathode lamp by discharging molecular oxygen (enriched in about 45% of the 17O2 isotope) under 1.0 Torr pressure. The rotational analysis of the 2-4, 2-5, and 2-6 bands was performed with the effective Hamiltonian of Brown (Brown et al., J. Mol. Spectrosc. 1979; 74: 294-318). Molecular constants were derived from a merge calculation, including both the current wavenumbers and the spectroscopic data published by the authors previously. The principal equilibrium constants for the ground state of 12C17O+ are ωe=2185.9658(84), ωexe = 14.7674(11), Be=1.927001(38), αe=1.8236(22) × 10-2, γe=-0.331(28) × 10-4, De=6.041(12) × 10-6, βe=0.100(31) × 10-7 cm-1, and the equilibrium constants for the excited state are σe=45876.499(15), ωe=1712. 201(12), ωexe=27.3528(39), Be=1.754109(35), αe=2.8706(57) × 10-2, γe = -1.15(19) × 10-4, De=7.491(20) × 10-6, βe=2.13(12) × 10-7, γe = 2.0953(97) × 10-2, and αγe=-9.46(59) × 10-4 cm-1, respectively. Rydberg-Klein-Rees potential energy curves were constructed for the B2Σ+ and X2Σ+ states of this molecule, and Franck-Condon factors were calculated for the vibrational bands of the B-X system. Copyright © Taylor & Francis Group, LLC.