2005 YU55 close approaches

From Jon Giorgini, Oct 29, 2011:
The following table lists planetary approaches within 0.1 AU, bounded 
in the past and future by the Earth encounters where the uncertainty in 
encounter time first exceeds +/- 10 days (3-sigma), or encounter distance 
exceeds +/- 0.1 AU, whichever occurs first. Prior to the 2011 radar 
experiment, this time-span is 1827 to 2011.

Although there are "possibilities", prior to the radar experiment we 
cannot confidently predict when the next such close encounter with Earth 
might occur. This is because close encounters with Earth in 2011, and 
Venus in 2029 increase prediction uncertainty.

Radar measurements from this experiment will reduce prediction uncertainty 
and permit meaningful Earth encounter predictions to be extended further 
into the future. 
                             (AU)     (AU)     (AU)  (km/s) (min.)
   Date (CT)       Body   CA Dist  MinDist  MaxDist   Vrel  TCA3Sg   P_i/p
-----------------  -----  -------  -------  -------  ------ ------  -------
1782 Nov 03.90961? Earth  .001927  .001826  .613831  13.742 42884.  .000000
....
1803 Jan 22.33074  Mars   .043688  .030690  .133335   5.472 32538.  .000000
1806 Nov 28.83813  Mars   .037160  .032034  .042972   4.863 37913.  .000000
1810 Oct 05.43562  Mars   .047549  .044064  .051502   5.567 5191.9  .000000
1813 Sep 20.03762  Venus  .027439  .003028  .072738  12.565 6290.8  .000000
1814 Dec 23.75657  Venus  .039899  .006320  .088827   9.613 15698.  .000000
1816 Apr 05.66252  Venus  .075503  .069533  .082533   9.348 22336.  .000000
1817 Jul 19.70019  Venus  .062431  .049074  .084977   9.246 15278.  .000000
1818 Oct 26.05852  Venus  .041058  .038266  .059462  11.834 4926.6  .000000
1827 Apr 16.92106  Earth  .018103  .013581  .022599  14.216 309.80  .000000
1858 Apr 21.43025  Earth  .073596  .072411  .074784  11.466  81.05  .000000
1864 Nov 04.60067  Earth  .015106  .014912  .015301  13.228  13.59  .000000
1868 Dec 19.42163  Mars   .035392  .035386  .035398   4.823  38.31  .000000
1872 Nov 06.10338  Mars   .095370  .095348  .095392   6.504   4.94  .000000
1890 Nov 03.09813  Earth  .061731  .061480  .061981  11.792  18.48  .000000
1891 Nov 03.37622  Venus  .068179  .067926  .068432  14.625  24.10  .000000
1893 Jan 28.02975  Venus  .038557  .038371  .038744  13.172  22.20  .000000
1894 Apr 23.94700  Venus  .021480  .021416  .021544  12.344   9.01  .000000
1895 Jul 16.98278  Venus  .024894  .024779  .025009  12.520  15.47  .000000
1896 Oct 06.48044  Venus  .047234  .047017  .047451  13.607  23.81  .000000
1897 Dec 27.52431  Venus  .080815  .080542  .081089  15.239  23.90  .000000
1933 Jan 02.17018  Mars   .056921  .056891  .056951   5.335  18.38  .000000
1949 Apr 14.17919  Earth  .090399  .090300  .090498  16.282   6.57  .000000
1957 Jun 12.69401  Mars   .051513  .051475  .051551   5.169  30.60  .000000
1984 Dec 05.94302  Venus  .048640  .048585  .048695  12.703  11.14  .000000
1986 Feb 21.62180  Venus  .043931  .043902  .043961  10.192  16.09  .000000
1987 May 04.38269  Venus  .071146  .071124  .071167   9.243  24.19  .000000
1988 Jul 11.93138  Venus  .080562  .080560  .080564   9.438  21.19  .000000
1989 Sep 19.89067  Venus  .065809  .065795  .065823   9.292  12.23  .000000
1990 Dec 01.43515  Venus  .028811  .028800  .028822  10.115   3.15  .000000
1992 Feb 17.98617  Venus  .012636  .012628  .012644  11.975   1.25  .000000
1993 May 06.14822  Venus  .093596  .093587  .093605  15.903   0.73  .000000
2002 Jul 14.60371  Mars   .039709  .039709  .039710   4.684   0.96  .000000
2010 Apr 19.51424  Earth  .015194  .015194  .015194  13.124   0.00  .000000
2011 Nov 08.97848  Earth  .002173  .002172  .002174  13.716   0.03  .000000
2011 Nov 09.30173  Moon   .001602  .001601  .001603  13.509   0.02  .000000
2027 Oct 20.64160  Venus  .088563  .087822  .089304  15.414  63.75  .000000
2029 Jan 19.78509  Venus  .001965  .001730  .002365  11.158 125.08  .000000
2030 May 27.61576  Venus  .064356  .052808  .082007   9.114 15475.  .000000
....
2041 Nov 06.06984? Earth  .033621  .001798  .314045  12.662 20465.  .000000

 Column meaning:
 
 Date (CT) =
   Nominal close-approach date (Coordinate Time) in the Gregorian calendar
system.

 Body =
   Name or abbreviation of the planetary body or major asteroid being
closely approached by the selected small-body.

 CA Dist =
   Nominal geometric close-approach distance at the close-approach time,
uncorrected for light travel time.  Units: AU

 MinDist =
   Minimum close-approach distance possible (formal 3 standard-deviations
with linearized covariance mapping). Units: AU

 MaxDist =
   Maximum close-approach distance possible (formal 3 standard-deviations
with linearized covariance mapping). Units: AU

 Vrel =
   Relative velocity of the object and the body it is approaching at the
nominal time of close-approach. Units: KM/S

 TCA3Sg =
   Close-approach-time 3-standard deviation uncertainty.  Units: MINUTES

 Nsigs  =
   The number of standard deviations (sigmas) required for the error ellipse
to intersect the body being closely approached. Units: STANDARD DEVIATIONS

 P_i/p  =
   Linearized probability of the object impacting the body.

                         +++++++++++++++++++++++++++++

 IMPORTANT NOTE:

   All tabulated statistical quantities (MinDist, MaxDist, TCA3Sg, Nsigs and
P_i/p) are based on a linearized covariance mapping in which higher-order
(small) terms in the variational partial derivatives of the equations of motion
are dropped.

   Due to possible non-linearities in any given object's actual dynamics, this
can result in significant errors at epochs distant in time from the solution
epoch.  Consequently, long linearized mappings (thousands, or hundreds, or
sometimes just dozens of years from the present time) should be considered
approximate, pending additional analysis, especially in these cases:

           A) objects with numerous close planetary encounters (dozens),
           B) objects with very close planetary encounters (< 0.01 AU),
           C) objects with very short data arcs (days or weeks).

   While linearized projections will tend to indicate such cases with obviously
rapid uncertainty growth, the specific numbers output can tend to understate
orbit uncertainty knowledge.

   "Nominal" here effectively means "highest-probability for the given orbit
solution"), although there can be other possible orbits of equal probability.
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