37th DPS Meeting, 4-9 September 2005
Session 15 Asteroid Physical Studies
Poster, Monday, September 5, 2005, 6:00-7:15pm, Music Recital Room

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[15.25] The Las Campanas/Lowell Observatory 2004 Itokawa Campaign

J. E. Thomas-Osip (OCIW/LCO), S. M. Lederer (NASA/JSC and CSUSB), D. Domingue (JHU/APL), D. J. Osip (OCIW/LCO), F. Vilas (NASA/JSC), K. Jarvis (Lockheed-Martin), S. Gill (CSUSB)

In 2004, Asteroid 25143 Itokawa made its final close approach to the Earth prior to its encounter, anticipated in the fall of 2005, with the Japanese spacecraft Hayabusa. An extensive visible and near-IR observing campaign of Itokawa was undertaken at Las Campanas Observatory in Chile yielding 18 nights of UBVRI photometric observations with simultaneous JHK observations on 9 of those nights. The visible observations were made using the Swope 1-m telescope and the near-IR observations were made using the duPont 2.5-m telescope. Throughout June and July 2004, the entire rotational period and phase angles between 11-90 degrees were sampled. Additionally, we obtained 9 nights of BVRI broadband photometry data in January and February 2004 at Lowell Observatory with the 1.7-m Perkins Telescope and further BVRI observations with the Magellan 6.5-m telescopes in both January and June to extend the phase angle coverage to a range from 4 degrees out to 130 degrees. This apparition was superb with Itokawa reaching magnitude 12 (two magnitudes brighter than the 2001 apparition) and covering a large range of observable phase angles.

The combined multi-wavelength (UBVRIJHK) rotational light curve allows for the concrete deconvolution of shape from albedo variation in the rotational models. This provides data that are ideally suited for a Hapke model study to investigate the surface scattering properties, such as single particle scattering albedo and phase function. With data reaching out to 4 and 130 degrees phase angle, we can also constrain the backscattering properties and surface roughness, respectively. This was previously impossible since in the 2001 apparition the asteroid was not observed at phase angles less than 10 or larger than 90 degrees. Additionally, broadband colors and the full U-K spectrophotometric trend are presented.

The authors at NASA would like to acknowledge the support of the NASA Hayabusa Program.

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Bulletin of the American Astronomical Society, 37 #3
© 2004. The American Astronomical Soceity.