Left panel: DECam coadded image of NCG4993 in gri. Shell structures indicative of a recent galaxy merger are clearly visible. Middle panel: r-band residuals from GALFIT after subtraction of the best-fit single Sérsic light profile. Right panel: F606W-band HST ACS image with a 3 component galaxy model subtracted. Dust lanes crossing the centre of the galaxy are evident after this subtraction. The green lines show the position of the transient. The white bar in each panel shows the 5 kpc scale.