Temporal evolution of total photospheric magnetic energy injection for AR 12473 from 23:36 UT on December 23, 2015 to 08:36 UT on January 2, 2016. The black dot and black star represent the flux rope formation time and the time when the flux rope reaches ≈100 Mx for various values of U and Ω. These are (a) the unmasked U-assumption, (b) the masked U-assumption, (c) the unmasked Ω-assumption, and (d) the masked Ω-assumption. The free parameters in the non-inductive electric field values vary from 0.25× to 4× of the optimised values. The DAVE4VM reference is also shown in solid black. The vertical dashed line is the M1.9 class flare peak time on Dec. 28, 2015.