asteroid: 2001 XR254
   satellite: companion 
total number: 7
        type: position
       dates: 2006-2007
 observatory: 250 - Hubble Space Telescope (HST)

Grundy W. M., Noll K. S., Buie M. W., Benecchi S. D., Stephens D. C., 
Levison, H. F.
Mutual orbits and masses of six transneptunian binaries
Icarus.2009. V. 200. Issue 2. P. 627-635.

         relative to: primary
     reference frame: astrometric ICRF
     centre of frame: topocentre
    epoch of equinox: J2000
          time scale: UTC
           reduction: not available
         coordinates: r, R, g, X, Y (secondary relative to primary)
            receptor: CCD
           telescope: 1 - HST HRC/ACS (High-Resolution Camera of the Advanced Camera for Surveys)
                      2 - HST WFPC2/PC (Planetary Camera of the Wide Field and Planetary Camera 2)
1."0.0" means the absence of data 

  1. Year of the moment of observation
  2. Month of the moment of observation
  3. Day of the moment of observation
  4. Hour of the moment of observation with decimals
  5. Ntel - the number of telescope
  6. r(au) - the distance from the Sun to the target  
  7. R(au) - the distance from the observer to the target
  8. g(deg) - the phase angle, the angular separation between the observer and Sun as seen from the target
  9. X(arcsec) - relative right ascension.
 10. sigma(X)(arcsec) - 1-sigma uncertainties X
 11. Y(arcsec) - relative declination
 12. sigma(Y)(arcsec) - 1-sigma uncertainties Y
 13. Vprim - visual magnitude for primary body
 14. sig(Vprim) - 1-sigma uncertainties Vprim
 15. Vsec - visual magnitude for secondary body
 16. sig(Vsec) - 1-sigma uncertainties Vsec

Year    Day  hour  Ntel   r      R      g      X      sigma(X)    Y      sigma(Y)  Vprim sig(Vprim) Vsec  sig(Vsec)
   Month                 AU     AU     deg   arcsec   arcsec    arcsec    arcsec     mag    mag     mag    mag