LT “mass–meter” for the observed periodicity P = 2825 s. The curves show the BH mass M_• implied by a precession radius ﹩\tilde{r}\equiv r/{r}_{{\rm{g}}}﹩ for spins a_* = {0.3, 0.5, 0.9}. The horizontal dashed lines mark the IMBH band (10⁴–10⁶ M_⊙); the dotted lines mark the stellar-mass band (3–30 M_⊙); and the thin solid line highlights a GRB scale M_• = 6 M_⊙. For ﹩\tilde{r}\sim 10\,\unicode{x02013}\,50\,{r}_{{\rm{g}}}﹩, the period selects the IMBH regime; achieving the same period with a ∼6 M_⊙ engine requires ﹩\tilde{r}\gtrsim 200\,\unicode{x02013}\,400\,{r}_{{\rm{g}}}﹩ or a different precession driver.