Effect of LED temperature on light flux (warming of CFHT dome at dawn): a) variable exposure (1s < Δt < 8s); b) constant exposure (Δt = 8s): two independent estimators ⟨ α_k ⟩≈ 16 000 adu (black points) and ⟨ Ψσ_δ ⟩≈ 100 adu (red points) agree within 0.8 × 10^-4 rms. Deviation from linearity is 1.8 × 10^-4 rms. The precision on ⟨ Ψσ_δ ⟩ is ≈0.008 adu, i.e., 0.6 × 10^-6. Error bars cover gain spread before averaging. The two other estimators ⟨ Ψσ_β ⟩ and ⟨ Ψσ_γ ⟩ (green and blue) are more sensitive to LED jitter.