'Larson-Sekanina' Filter Applied to 17P/Holmes
The Larson-Sekanina filter is an algorithm devised in 1984 by Steven Larson and Zdenek Sekanina of the Jet Propulsion Laboratory to reveal hidden variations of brightness in comets. You may read about this algorithm here. I have applied a simplified version of this filter to the head of 17P/Holmes using a combination of a 2o counter-clockwise rotation and a 2o clockwise rotation. Although this technique produces artifacts from stars and other structures, it does faithfully reveal aspects of a comet such as jets and shock fronts. In the filtered image below the stars show as a bright spot with a dark spot on either side. The comet has a jellyfish-like appearance. The bright dot at the center of the comet is the head of the comet. The white and black streaks emanating from the comet head to the lower left are jets of material being blown away from the comet head. Some rope-like structure is also revealed on the leading edge of the comet. The bottom image on this page shows how this relates to the color image of the comet.
Mouse-over to see the Larson-Sakanina filter overlaid on the color image of the comet head.
Click mouse-over image to return.