Fiber Bragg gratings fabricated in pristine SMF-28e fibers using pulsed ArF-excimer and cw 244-nm Ar+ laser were annealed using tempering rates from 0.0038 to 0.25 K/s. Demarcation energy mapping allowed for the determination of the frequency factors and the master curves for the SMF-28e fiber under different irradiation conditions. A Gaussian decomposition of the underlying energy distribution revealed several individual activation energy distributions characteristic for the fiber with peak energies and widths that were independent of the laser used. From a fit of the integrated Gaussian distributions to the master curves the relative contributions of the individual energy distributions that appeared in both irradiation conditions were calculated. The difference in the activation energy spectra obtained from the two laser irradiations are explained by the relative contributions of the individual distributions that differ. Using the analytical description of the master curve, thermal stability maps were obtained.