MUSE object #2277. Top panel: spectrum which shows a clear Ly-α line at z = 3.335. The narrow-band image over this line is shown in the bottom left. Following three images in the bottom row: HST images in F775W, F606W and F435W. The Ly-α narrow-band image is overlaid as contours in the F775W image with contours at approximate S/N per pixel of 2, 3, 4 and 5 shown and the centroid of the narrow-band image indicated by a cross. The two central HST objects from the R15 catalogue are labelled in the F606W image and it is clear that the narrow-band image is extending across both objects. A comparison of the F775W and F435W images also shows that these objects have similar colours.