C/2011 R1 McNaught
more info
Comet C/2011 R1 was discovered on 3 September 2011 by Robert H. McNaught (Siding Spring), that is more than a year before its perihelion passage. It was observed until 11 April 2014.
Comet had its closest approach to the Earth on 8 April 2013 (1.960 au), 5.5 months after its perihelion passage; however on 8 August 2012 (2.5 months before perihelion) the comet approached the Earth only a little further (2.035 au, see picture).
Solution given here is based on data spanning over 3.5 yr in a range of heliocentric distances: 7.47 au – 2.08 au (perihelion) – 5.91 au.
This Oort spike comet suffers tiny planetary perturbations during its passage through the planetary system that cause a bit tighter future orbit with original semimajor axis of about 10,000 au (see future barycentric orbits).
See also Królikowska 2020.

solution description
number of observations 1504
data interval 2010 10 11 – 2014 04 11
data type perihelion within the observation arc (FULL)
data arc selection entire data set (STD)
range of heliocentric distances 7.47 au – 2.08 au (perihelion) – 5.91 au
type of model of motion NT - non-gravitational orbits for asymmetric, standard g(r)
data weighting YES
number of residuals 2909
RMS [arcseconds] 0.37
orbit quality class 1a+
previous orbit statistics, both Galactic and stellar perturbations were taken into account
no. of returning VCs in the swarm 5001 *
no. of escaping VCs in the swarm 0
no. of hyperbolas among escaping VCs in the swarm 0
previous reciprocal semi-major axis [10-6 au-1] 44.41 – 45.20 – 45.92
previous perihelion distance [au] 380 – 440 – 490
previous aphelion distance [103 au] 43.2 – 43.8 – 44.5
time interval to previous perihelion [Myr] 3.18 – 3.28 – 3.37
percentage of VCs with qprev > 20100
Upper panel: Time distribution of positional observations with corresponding heliocentric (red curve) and geocentric (green curve) distance at which they were taken. The horizontal dotted line shows the perihelion distance for a given comet whereas vertical dotted line — the moment of perihelion passage.
Lower panel (panels): O-C diagram for this(two) solution (solutions) given in this database, where residuals in right ascension are shown using magenta dots and in declination by blue open circles.
previous orbit statistics, here only the Galactic tide has been included
no. of returning VCs in the swarm 5001 *
no. of escaping VCs in the swarm 0
no. of hyperbolas among escaping VCs in the swarm 0
previous reciprocal semi-major axis [10-6 au-1] 44.66 – 45.49 – 46.38
previous perihelion distance [au] 1.01 – 1.06 – 1.11
previous aphelion distance [103 au] 43.1 – 44 – 44.8
time interval to previous perihelion [Myr] 3.16 – 3.26 – 3.35
percentage of VCs with qprev < 10100