*5.3. Energy-Resolved Measurements*

To date, no energy-resolved polarization measurements for GRBs have been performed. This is mainly a result of the low statistical significance found for the existing measurements. Dividing the data into energy bins would further reduce the available statistics and therefore not allow for constraining measurements to be performed. A secondary issue with such measurements is the difficulty in the analysis for many of the polarimeters. Unlike in spectrometers, a significant number of the detected photons in a polarimeter are not fully contained in the detector. After a first Compton scattering interaction, a second scattering interaction can follow, after which the photon escapes. As a result, there is a large uncertainty on the incoming photon energy. The analysis is therefore not as simple as dividing the available polarization events based on the energy they deposited in the detector. Instead, one needs to take into account the energy dispersion and use, for example, forward folding methods using an energy-dependent polarization response. Although possible, such methods have not yet been applied to date. It should be noted that for certain instruments, such as COSI, Compton kinematics can be applied to ensure only fully contained photons are selected in the analysis. This significantly reduces the issue of energy dispersion; however, for a proper handling of the data, an energy-dependent polarization response is still required for energy-dependent polarization measurements.
