Left panel: inferred shocked mass (black) and electron density (blue) of the CSM region as a function of the distance. Right panel: age of the CSM region estimated adopting the Sedov-Taylor (Sedov 1959; Taylor 1950) solution and assuming density in the LOFAR ring is the same as the one we measured from the X-rays (green, orange, and blue dashed lines indicating explosion energies of 10⁵⁰, 10⁵¹, and 10⁵² erg). The solid black line indicates the age estimated using τ. The red, yellow, and brown areas mark the allowed distances. See text for details.