Spectrum of HD 254577 with the overlaid model spectra of T_eff = 23 000, 24 000, and 25 000 K with a fixed surface gravity of log(g [cm/s²]) = 2.75, a projected rotation velocity of v sin i = 150 km s⁻¹, and a single micro-turbulence velocity of ξ = 10 km s⁻¹. Top Left: Wavelength range of 4075 − 4140 Å. Si  IVλ4089, 4116 lines are prominent temperature indicators. The spectrum is consistent with the T_eff = 24 000 K model at the Si  IVλ4116/ He  Iλ4121 ratio. Top Right: Wavelength range of 4540 − 4660 Å. The spectrum is once again consistent with the T = 24 000 K model at the Si  IVλ4089/ Si  IIIλ4553 ratio. Bottom Left: Wavelength range of 4670 − 4725 Å. The spectrum is once again consistent with the T_eff = 24 000 K model at the He  IIλ4686/ He  Iλ4713 ratio. Bottom Right: Spectrum of HD 254577 with the model spectrum of T_eff = 24 000 K, log(g [cm/s²]) = 2.75, and ξ = 10 km s⁻¹ overlaid.