Scientists used Suprime-Cam at Subaru Telescope to catch the comet 103P/Hartley.

Since the distance to the comet from the Earth is small and the apparent movement of the comet on the sky is large, non-sidereal tracking was used during this observation based on the orbital parameters of the comet.

The image is composed from the dataset of three different filters;

• Green g'-band (480nm),
  
• Red r'-band (620nm)
• Far-infrared z'-band (900nm)

The filters have been colour coded and is allotted for blue, green, and red, respectively.

Since the comet was moving from the lower right to the upper left compared with the background stars, each background star appears as triple points with three colors along the direction of the comet movement.

Sourec: Subaru telescope homepage