C/2011 Q2 McNaught
more info
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
type of model of motion NS - non-gravitational orbits for standard g(r)
data weighting YES
number of residuals 202
RMS [arcseconds] 0.21
orbit quality class 2a
orbital elements (heliocentric ecliptic J2000)
Epoch 2011 09 13
perihelion date 2012 01 19.79781850 ± 0.00324154
perihelion distance [au] 1.34949376 ± 0.00008294
eccentricity 0.99989009 ± 0.00008723
argument of perihelion [°] 34.635210 ± 0.004464
ascending node [°] 287.369505 ± 0.000930
inclination [°] 36.866976 ± 0.000211
recip semi-major axis [10-6 au-1] 81.44 ± 64.64
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
non-gravitational parameters
A1 [10-8au\day-2] 1.6201 ± 4.1081
A2 [10-8au\day-2] 2.9754 ± 1.608
A3 [10-8au\day-2] -0.52438 ± 0.52716
m -2.15
n 5.093
k -4.6142
r0 [au] 2.808
α 0.1113