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
orbital elements (barycentric ecliptic J2000)
Epoch 1713 05 18
perihelion date 2012 01 20.11290898 ± 0.00125057
perihelion distance [au] 1.35273854 ± 0.00000323
eccentricity 1.00001563 ± 0.00001927
argument of perihelion [°] 34.550117 ± 0.000589
ascending node [°] 287.383297 ± 0.000120
inclination [°] 36.855334 ± 0.00009
reciprocal semi-major axis [10-6 au-1] -11.56 ± 14.24
file containing 5001 VCs swarm
2011q2a5.bmi
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.
Six 2D-projections of the 6D space of original swarm including 5001 VCs. Each density map is given in logarithmic scale presented on the right in the individual panel.