12CO+ and 13CO+ fluorescence models for measuring the 12C/13C isotopic ratio in comets P. Rousselot, E. Jehin, D. Hutsemékers, C. Opitom, J. Manfroid and P. Hardy A&A, 683 (2024) A50 Published online: 05 March 2024 DOI: 10.1051/0004-6361/202348027