Flyby of Asteroid 1998 WT24 on December 16, 2001 (UT)
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On the weekend of December 15-16, 2001, asteroid 1998 WT24 made a close approach to earth. While there was no danger of this asteroid striking the earth on this pass (it missed the earth by about five times the distance between the earth and moon), this was a relatively close pass. This asteroid is thought to be about a kilometer in diameter, so if it HAD hit the earth (or does some day in the future), it would cause devastation on a regional level.
On any given clear evening, dozens to hundreds of asteroids are visible through a medium-sized amateur telescope. Most appear to move relatively slowly (because of their great distance from earth), so any motion relative to the stars can only be discerned over a period of hours to days. Because this asteroid was passing so close to earth, it appeared to move much more quickly. In fact, its motion was apparent through the eyepiece in as little as 30 seconds or so!
Below is a series of images I took of 1998 WT24 passing near a pair of stars over a period of about 3 minutes. The images were taken with an STV CCD camera. The time stamp in each image is only approximate, as I did not synchronize with WWV before starting to record, however the time stamps should be within a few seconds of correct. The time shown is Eastern Standard Time.
In each image, the exposure was 10 seconds long. During that time, the asteroid moved enough that it appears elongated. It passes very close to a star, which I believe is GSC 2881:189 (mag. 11.18 according to The Sky). The lower star would then be GSC 2881:97 (mag. 11.56). The asteroid was about mag. 9.65 at the time of these exposures. North is up and east is left. All images were taken at prime focus of my 10" f/10 LX200, with the STV in "normal" mode.
Asteroid just misses the star!
|Asteroid continues on its merry way|
The entire sequence above lasted less than 2-1/2 minutes.
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