Noise level associated with each Fe XVI spectral line at all times in regions 1 to 7. A 1-sigma Gaussian noise level for each region at each time is calculated using noise(%) = STD(ϵ/I) × 100. As expected the noise level falls as the line intensity increases during the flare times of ~01:25 UT to 02:30 UT. The 1-sigma noise level is less than 10% during all flare times, and as low as 2% during peak flare times. Our studied flare time of 01:41:16 UT is shown by the grey band, with noise levels between ~3−5% (shown by the black dotted lines).