Results of the forward modeling of the β Pic b GRAVITY spectrum. The combined GRAVITY spectrum (in black) compared data from the other panels in this figure. First panel: best-fit Exo-REM (in blue). Second panel: best-fit ATMO (in green). Third panel: best-fit BT-Settl (in red). Fourth panel: best-fit Sonora (in yellow). The two ¹³CO absorption lines are annotated at 2.345 µm and 2.374 µm; the four ¹²CO lines at 2.294 µm, 2.323 µm, 2.352 µm and 2.383 µm as well as the two H₂O band heads between 1.75–2.05 µm and 2.3–3.2 µm. Bottom panel: residuals for each fit. Dotted lines represents the ±σ (68%) confidence interval.