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This series of images of comet C/2012 S1 (ISON) was taken by the Medium-Resolution Imager of NASA's Deep Impact spacecraft over a 36-hour period on Jan. 17 and 18, 2013. At the time, the spacecraft was 493 million miles (793 million kilometers) from the comet.
JPL, a division of the California Institute of Technology in Pasadena, manages the Deep Impact mission for NASA's Science Mission Directorate, Washington. The University of Maryland is the Principal Investigator institution for the mission. Deep Impact is part of the Discovery Program managed at NASA's Marshall Space Flight Center in Huntsville, Ala. The spacecraft was built for NASA by Ball Aerospace & Technologies Corp., Boulder, Colo.
For more information about Deep Impact, visit: http://solarsystem.nasa.gov/deepimpact.