On 6th February 2001, a comet was discovered that fell into the Sun a day later. A series of pictures were taken by the SOHO spacecraft, which I downloaded and processed to see if a higher resolution image could be produced.
I downloaded the series of publically-available images from the C3 instrument on board the SOHO spacecraft that contained pictures of the comet. The comet starts out as a very faint blob, in the lower-left corner of the images.
The first image to show the comet was taken at 1142 on the 6th February 2001. The last proper image to show the comet before it disappeared into the Sun was at 1542 on the 7th February 2001. I took three sets of four contiguous images each - the first image of each set was taken at 1142/06, 0242/07 and 1242/07, respectively.
With each set of four images, I cut out the image of the comet and lined up the centre of the comet nucleus. I then quadrupled the image dimensions and passed each one through a gaussian blur filter. The blurred images were then combined with an averaging operator to produce three final images (one product from each set of four).
An example image from each of the three sets is shown below:
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| Fig 1. First image of the comet, set 1, taken at 1142/06 | Fig 2. Comet gets closer to sun, exhibits slight tail, set 2, taken at 0242/07 | Fig 3. Comet near to the sun, tail is more visible, set 3, taken at 1242/07 |
The resulting image from each of the three sets is shown below:
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| Fig 4. Result of the first set of images - the coma is visible. | Fig 5. Second set - the tail is much more prominent. | Fig 6. Third set - the tail is easily visible. |
The results from the first set of images showed the coma much more clearly through the 'noise' of the raw images.
The combination of the final set of four images brought out some detail from the tail of the comet that was not easily visible from the raw images. Combinations of more than four images should improve the results.
There are certainly better ways to combine the images - using specially crafted filters, or different combination operators, but for a first experimental attempt that took only a couple of hours by hand, the results were ok.
Now look at the article at SpaceFlightNow.com (link below) to see the results of the UVCS (ultraviolet coronagraph spectrometer) instrument that was able to take much higher resolution pictures of the comet. (The raw images from the UVCS instrument were not available to the public at the time.)
Article at Spaceflightnow.com - http://www.spaceflightnow.com/news/n0102/23soho/
Main SOHO site - http://sohowww.nascom.nasa.gov/
SOHO image archive - http://sohowww.nascom.nasa.gov/data/realtime/realtime-c3-1024-all.html (though don't hammer that one, use a mirror, like this European one, instead.)
Images appear courtesy of SOHO/LASCO consortium. SOHO is a project of international cooperation between ESA and NASA.
25th February 2001
