A new measurement of the Galactic 12C/13C gradient from sensitive HCO+ absorption observations Gan Luo, Laura Colzi, Tie Liu, Thomas G. Bisbas, Di Li, Yichen Sun and Ningyu Tang A&A, 690 (2024) A372 Published online: 29 October 2024 DOI: 10.1051/0004-6361/202451412