Comparison of spectra from PSR B1259–63/LS 2883’s 2021 periastron passage. Shown is the total spectrum of the 2021 periastron passage compared to two sub-spectra. Each model was calculated with the forward-folding method, using a power law in an energy range of (0.4 − 10.0) TeV to allow a comparison between them. Comparing spectra allowed us to search for VHE spectral variability on the scale of a single periastron passage. Displayed in red (black circles) is the spectrum of the total 2021 periastron passage, in cyan (cyan diamonds) the spectrum from the dataset D and in magenta (magenta triangles) the spectrum of dataset B. For details on the properties of the spectra displayed see Table 2. Shaded regions indicate the 68% c.i. for the fitted model.