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David J. Tholen is an American astronomer at the Institute for Astronomy of the University of Hawaii, who specializes in planetary and solar system astronomy. Tholen has discovered a number of asteroids, including the lost 1998 DK₃₆, which may be an Apohele asteroid, and 2004 XZ₁₃₀, which certainly is; in fact, it has the smallest semimajor axis and aphelion distance among the known asteroids. He won the H. C. Urey Prize in 1990.

He co-discovered the asteroid 99942 Apophis (previously known as 2004 MN₄). This asteroid will closely approach the earth on 13 April 2029 and very briefly appear as bright as a third magnitude star.

In 1995, Tholen obtained images of the newly-discovered comet Hale-Bopp at a time when the comet was moving very slowly with respect to the background stars, thus permitting the red- green- and blue-filtered images to be combined into a color composite without the background stars appearing as separately colored dots. This color composite image was made publicly accessible via his Institute's web site.

Later, Olivier Hainaut discovered that this image was nearly identical to the one being discussed by late-night radio host Art Bell and one of his guests, Courtney Brown, who claimed that the image proved the existence of an unnatural object following the comet, something supposedly seen by those who had learned how to engage in the technique of "remote viewing". The image provided to Bell by Brown, and eventually made public on Bell's web site, did indeed show an object next to the comet that did not appear in archival images of the sky. In reality, the original image obtained by Tholen had been digitally altered, presumably by taking the image of a star near the edge of the frame, adding it to image next to the comet, and then trimming away the outer edges of the frame.

Tholen and Hainaut exposed the fraud by producing the original image, which showed no such additional object. Nevertheless, some people maintained that Brown's version was the original image and that Tholen had removed the additional object from the one on the Institute's web site. Indeed, the Heaven's Gate cult was so convinced that the additional object was a spaceship coming to take them away from Earth that they committed mass suicide.

• Homepage
• Tholen responds to faked images

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