Date: 07 Jan 2004
Satellite: Hubble
Depicts: M81, Supernova 1993J
Copyright: Credit: ESA and Justyn R. Maund (University of Cambridge)

The image is taken with Hubble's Advanced Camera for Surveys and is a combination of four exposures taken with ACS' High Resolution Camera. The exposures were taken through two near-UV filters (250W, 2100 seconds and 330W, 1200 seconds) shown in purple and blue, a deep blue filter (435W, 1000 seconds) shown in green and a green filter (555W, 1120 seconds) shown in red.

The quarter-circle around the supernova companion is a so-called light echo originating from sheets of dust in the galaxy reflecting light from the original supernova explosion. The timing of the appearance of these echoes can be used to map out the dust structure around the supernova. The light echo was detected in late 2002 and early 2003 by two competing groups of scientists.