An easier piece of blink-comparison

December 12 21:15	December 16 23:10

The hard bit is pointing the camera at the right anonymous group of faint stars that the asteroid you're looking for was near last time. Mars is much easier to find, being the brightest object in the sky except the Moon; at the same scale, and over the same time period, it moves a good deal further than Ceres did, confirming that Ceres is further away.