Validation of open-source science tools and background model construction in γ-ray astronomy L. Mohrmann, A. Specovius, D. Tiziani, S. Funk, D. Malyshev, K. Nakashima and C. van Eldik A&A, 632 (2019) A72 Published online: 02 December 2019 DOI: 10.1051/0004-6361/201936452