Upper limits to the extinction-corrected optical fluxes of PSR J1028 − 5819 compared with the low-energy extrapolations of the X-ray and γ-ray PLs that most closely fits the Suzaku and Fermi (Abdo et al. 2009a) data (black solid lines). The yellow and blue-shaded areas indicate the 1σ uncertainty in the extrapolations of the X and γ-ray PLs, respectively. The plotted optical flux upper limits are corrected for interstellar extinction based upon an N_H = 10²¹ cm^-2.