Asteroid Kleopatra light curve

[lukebl]

Hi folks,

This is my first attempt at measuring the light curve of an asteroid, and I'm quite pleased with the result. Thanks to Dave Smith for introducing me to Muniwin software, which was used to calculate the curves. 

I chose a known fast-rotating asteroid for my first attempt, 216 Kleopatra, to make it easier. It turns out that Kleopatra is very interesting. It is bone-shaped (217 × 94 × 81 km) and has two moons. Being bone-shaped, I figured that its magnitude would be pretty variable as it rotated, and I was right. It's currently easy to find in Aquila at around 11th magnitude.

I took a series of 30 second exposures over period of about three hours, and then processed it with Muniwin. I haven't yet figured out how to get the actual magnitude with the software, but it does show the magnitude of the asteroid relative to a reference star. As you see, the asteroid's magnitude changed smoothly by about half a magnitude over a period of about 90 minutes. A check with Astrometrica confirmed that at 20:10 its magnitude was about 10.8, falling to 11.3 at 21:40, and rising back to 10.9 at 22:22. There's an interesting little blip at about 20:50. Perhaps an additional irregularity in its shape?

Here's one of the 30-second frames

[Stu]

Fascinating stuff Luke, a great piece of work