Cutout of the bright radio shell of G190.9−2.2 corresponding to the box outlined on the 21 cm panel of Fig. 2, showing optical (red) emission from the Second Palomar Observatory Sky Survey (bright emission is shaded dark here). A thin compressed filament of red nebulosity is seen running parallel and next to the innermost 21 cm radio contour, which is the completely enclosed white contour in the centre (the three white contours here are the same as are in the 21 cm panel of Fig. 2). This filament likely traces shocked gas downstream of the SNR shock.