Figure 1: Mapping of the C/2013 A1 1 σ position uncertainty on the 2014 October 19 b -plane for sequential orbital solutions. Dashed ellipses are for earlier gravity-only solu- tions computed before the astrometry selection and remeasurement process described in Sec. 2.1: solution 46 includes data until 2014 March 31, while solution 56 includes data until 2014 August 11. Solution 95 and 97 are the two solutions computed before the 2014 October 7 HiRISE astrometry, while solution 101 is the final ephemeris delivery prior to the encounter. Finally, solution 102 is computed employing the Rotating Jet Model and using the full data arc through end of April 2015. −3.6 −3.4 −3.2 −3 −2.8 −2.6 x 10 4 −1.38 −1.36 −1.34 −1.32 −1.3 −1.28 −1.26 x 10 5 46 48 50 52 54 56 95 97 101 102 ξ  [km] ζ  [km] 6