HUTG: a next-generation IGS real‑time combined GIM via two‑step global and regional correction with robust weighting from HENU and UPC‑IonSAT. - Xu, Kualong; Liu, Qi; Hernández-Pajares, Manuel; Monte-Moreno, Enric; Yang, Heng; Olivares-Pulido, Germán; Roma-Dollase, David; García-Rigo, Alberto; Wang, Ningbo; Li, Zishen; Liu, Ang; Ubelmann, Clément; et al. (GPS Solutions, 2026)