Home > Uncategorized > Asteroid 2005 YU55 – Near Earth Fly-by Images

Asteroid 2005 YU55 – Near Earth Fly-by Images

On Novmber 8th and 9th, an asteroid the size of an aircraft carrier (as the media analogy went) passed by the Earth at less than the distance of moon.  The object was around magnitude 11 (too dim for binoculars, but easy for long-exposure imaging through a small telescope), and it covered almost 180 degrees of sky in two days.  Fortunately, the skies were clear here in New Jersey, and Sky & Telescope published excellent finder charts, so I was able to capture many images of it.

This is a composite of four of those images, covering six-and-a-half minutes, from 7:43 to 7:49pm local time, as the asteroid flew across the western side of the small constellation Delphinus.  (In fact, this may be the only time I ever have reason to take an image of this otherwise uninteresting area of sky!)  It was moving approximately 10 arcseconds per second, which is really fast for an astronomical object.  To capture these images, I had to ambush it, pointing the scope where it was expected to be about ten minutes ahead of schedule, waiting for it to cross the frame.  For a once-in-a-lifetime occurrence, I’m happy to have captured it.

These images show a fluctuation in brightness with a period of around 30 seconds.  This is not due to the gaps between exposures, which was only 10 seconds.  The fluctuation is visible even in the individual 90 second frames.  I assume this is due to the tumbling of the asteroid, but the “stretching” of the images’ brightness that I had to do is exaggerating the depth of the fluctuations.  I have not seen other images with this effect, but I have done everything I can to confirm that this is indeed the location and trajectory of this object at the time of the exposures.  In fact, I captured two more exposures of this object an hour later, also exactly where it was predicted to be, and those show the same fluctuations.

This is a composite of four 90 second exposures, uncalibrated (no flats or darks, as is obvious!), with a Canon XSi DSLR through a TMB 80mm f/6.3 refractor.  Mount was a CGEM.  These are from my front yard in Whitehouse Station, NJ.

Asteroid 2005 YU55 7:43 to 7:49pm EST, Nov 8, 2011

Asteroid 2005 YU55, 7:43 to 7:49pm EST, Nov 8, 2011

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