Sky images of 67P obtained from a single exposure. The phase angle and equivalent filter range are provided on top of each figure. Panel awas obtained with a 120-s exposure, while panels b and cwere obtained with a 60-s exposure. Panels a and b cover the FoV of 1′.0 × 1′.0, while panel cspans 2′.0 × 1′.2 to encompass the neck-line structure. North is up and east is to the left. The level of brightness was inverted and arbitrarily adjusted to enhance weak coma structures. The 1000-km-sized aperture applied in this study is overlaid as a magenta box, covering the inner coma part. The solid and dashed arrows denote the Sun–comet radius vectors and the comet’s negative heliocentric velocity vectors, respectively. Background structures are either stars or cosmic rays.