Description of the SHAPE MODEL OF ASTEROID (153591) 2001   
        SN263 bundle V1.0
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Bundle Generation Date: 2020-02-28
Peer Review: 2016 Shape Model Review, Sat Dec 31 00:00:00 MST 2016            
Discipline node: Small Bodies Node


Content description based on the data set catalog file description for the PDS3 version, EAR-A-I0037-5-SHAPE153591-V1.0
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Note: for PDS3 data sets migrated to PDS4, the following text is taken
verbatim from the data set description and confidence level note of the
PDS3 data set catalog file. In these cases, some details may not be correct
as a description of the PDS4 bundle.
                                                           
    We report radar observations (2380-MHz, 13-cm) by the Arecibo Observatory 
    and optical light curves observed from eight different observatories and  
    collected at the Ondrejov Observatory of the triple near-Earth asteroid   
    system (153591) 2001 SN263. The radar observations were obtained over the 
    course of ten nights spanning February 12-26, 2008 and the light curve    
    observations were made throughout January 12 - March 31, 2008. Both data  
    sets include observations during the object's close approach of 0.06558 AU
    on February 20th, 2008. The delay-Doppler images revealed the asteroid to 
    be comprised of three components, making it the first known triple        
    near-Earth asteroid. Only one other object, (136617) 1994 CC is a         
    confirmed triple near-Earth asteroid.                                     
                                                                              
    We present physical models of the three components of the asteroid system.
    We constrain the primary's pole direction to an ecliptic longitude and    
    latitude of (309,-80) degrees +/- 15 degrees. We find that the primary    
    rotates with a period 3.4256 +/- 0.0002 h and that the larger satellite   
    has a rotation period of 13.43 +/- 0.01 h, considerably shorter than its  
    orbital period of approximately 6 days. We find that the rotation period  
    of the smaller satellite is consistent with a tidally locked state and    
    therefore rotates with a period of 0.686 +/- 0.002 days (Fang et al.      
    [2011]. Astron. J. 141, 154-168). The primary, the larger satellite, and  
    the smaller satellite have equivalent diameters of 2.5 +/- 0.03 km, 0.77  
    +/- 0.12 km, and 0.43 +/- 0.14 km, and densities of 1.1 +/- 0.2 g/cm^3,   
    1.0 +/- 0.4 g/cm^3, and 2.3 +/- 1.3 g/cm^3, respectively.                 
                                                                              
    The shape models are presented as faceted solids in Wavefront .obj format.
    Also given are rendered .png images of the shapes and tabulated rotation  
    states. In the rendered mages, colored regions indicate areas that were   
    not well-viewed by the radar observations (incidence and emission angle > 
    60 degrees). These facets are listed in the 'unseen' tables.


Known issues or problems with the data
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    See Table 4 of Becker et al., 2015 for formal uncertainties.  The shape   
    models of beta and gamma were computed as spherical harmonic              
    representations. The models here are faceted realizations of those shapes.
    The coordinate system is not precisely aligned to the center of mass and  
    moments of inertia. In principle, offsets could be physically meaningful, 
    but they are within the uncertainties for this model.

PDS3 Source
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Version 1.0 of this bundle was migrated from version 1.0 of the PDS3 data set EAR-A-I0037-5-SHAPE153591-V1.0.