This small comet has been moving vertically towards the horizon, passing close to Theta Aurigae (bright star on the left) in this image. A difficult shot, with the comet barely peeking out above my hedge and with gathering cloud and orange light pollution. 21P shows up green in some people's images but is only faintly so here. The Starfish cluster can be seen on the right of the image. I have attempted to reduce the vignetting by the lens but it is still visible, albeit nothing like as bad as before.