Disclosed herein are a system, method, and computer-readable storage medium for determining a time pickoff for both digital and analog photomultiplier circuits. Rather than basing time pickoff on the leading edge of a photomultiplier signal crossing a threshold or the first signal from a digital photomultiplier, a method for more accurate time calculations is disclosed. The system searches for peak values associated with the signal using differentiation, peak hold searching, and Gaussian distributions. Based on these calculations and comparisons, a more accurate time pickoff is determined.