Moon around the primary asteroid (45)Eugenia
Ast09 The above infrared image is a composite of 5 detections of the new moon (taken -- clockwise from top -- on the nights of 1998 Nov 6,7,9,10 and 1). The green dashed line shows the orbit of the moon around the primary asteroid (45)Eugenia. The period of the orbit is 4.7 days.
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Image Credit: Laird Close (European Southern Observatory, Munich, Germany), Bill Merline (Southwest Research Institute, Boulder, Colorado, USA).  

The above infrared image is a composite of 5 detections of the new moon (taken -- clockwise from top -- on the nights of 1998 Nov 6,7,9,10 and 1). The green dashed line shows the orbit of the moon around the primary asteroid (45)Eugenia. The period of the orbit is 4.7 days. The moon travels in a closewise direction in this view. The radius of the nearly circular orbit is about 1200 km. The orbit is tilted about 45 degrees with respect to our line-of-sight, so it appears as an oval. The main asteroid is about 215 km in diameter and we estimate the moon's diameter to be 13 km. The moon is 300 times fainter than the asteroid. The large "cross" is a common artifact caused by stray light in the telescope, and is not a real object. Utilizing a new technology, called adaptive optics, we have been able to achieve images 6 times sharper than could otherwise have been obtained from the Earth's surface. Adaptive optics detects and removes the blurring caused by the Earth's atmosphere.  
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