C/2011 Q2 McNaught
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Comet C/2011 Q2 was discovered on 26 August 2011 by Robert H. McNaught (Siding Spring), that is almost 5 months before its perihelion passage. It was observed until 26 April 2012.
Comet had its closest approach to the Earth on 26 January 2012 (2.271 au), a week after its perihelion passage.
Solution given here is based on data spanning over 0.665 yr in a range of heliocentric distances: 2.43 au – 1.349 au (perihelion) – 1.94 au.
This Oort spike comet suffers notable planetary perturbations during its passage through the planetary system that cause a tighter future orbit with original semimajor axis of about 1,000 au (see future barycentric orbits).
See also Królikowska 2020.

solution description
number of observations 105
data interval 2011 08 26 – 2012 04 26
data type perihelion within the observation arc (FULL)
data arc selection entire data set (STD)
range of heliocentric distances 2.43 au – 1.35 au (perihelion) – 1.94 au
detectability of NG effects in the comet's motion comet with determinable NG~orbit
type of model of motion GR - gravitational orbit
data weighting YES
number of residuals 202
RMS [arcseconds] 0.22
orbit quality class 1b
previous orbit statistics, both Galactic and stellar perturbations were taken into account
no. of returning VCs in the swarm 119
no. of escaping VCs in the swarm 4882
no. of hyperbolas among escaping VCs in the swarm 3926 *
previous reciprocal semi-major axis [10-6 au-1] -29.15 – -11.03 – 6.87
previous perihelion distance [au] 4.1 – 5.4 – 7
previous aphelion distance [103 au] 110 – 320 – 2000
synchronous stop epoch [Myr] -1.75 S
percentage of VCs with qprev < 10100
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.
previous orbit statistics, here only the Galactic tide has been included
no. of returning VCs in the swarm 137
no. of escaping VCs in the swarm 4864
no. of hyperbolas among escaping VCs in the swarm 3931 *
previous reciprocal semi-major axis [10-6 au-1] -29.32 – -11.14 – 6.80
previous perihelion distance [au] 4.3 – 5.5 – 6.9
previous aphelion distance [103 au] 110 – 320 – 2100
synchronous stop epoch [Myr] -1.77 S
percentage of VCs with qprev < 10100