C/2007 Q3 Siding Spring
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Comet C/2007 Q3 was discovered on 25 August 2007 with Siding Spring survey; that is a bit more than 2 years before its perihelion passage. It was observed until 3 September 2011 (see picture).
Comet had its closest approach to the Earth on 2 February 2010 (2.193 au), about 4 months after its perihelion passage.
C/2007 Q3 is a comet with non-gravitational effects strongly manifested in positional data fitting. Preferred (non-gravitational) solution given here is based on data spanning over 4.02 yr in a range of heliocentric distances: 7.64 au – 2.252 au (perihelion) – 7.07 au. However, it was difficult to indicate the preferred model for this comet. Therefore, we show also second global non-gravitational solution based on g(r)-like function dedicated to CO (dc solution based on data taken at large heliocentric distances). In addition, there are two further solutions: NG orbit for pre-perihelion arc of data (g(r)-like function consistent with CO) dedicated for past orbital evolution, and a pure gravitational orbit based on post-perihelion data taken at heliocentric distances starting from 3.5 au and dedicated to future evolution. From the dynamical perspective, all these solutions give a fairly precise range of original 1/a values from 28 to 41 in units of 10-6 au-1. The solution given in the Nakano Notes (NG orbit) is also placed inside this range of original 1/a, but the MPC solution (GR orbit) results in a slightly lower value of original 1/a.
This Oort spike comet suffers rather large planetary perturbations during its passage through the planetary system and these perturbations lead to more tight future orbit (see future barycentric orbits).
See also Królikowska and Dybczyński 2013 and Królikowska 2020.

solution description
number of observations 699
data interval 2007 08 25 – 2011 09 03
data arc selection only data taken in large heliocentric distance (DIS)
range of heliocentric distances 7.64 au – 2.25 au (perihelion) – 7.07 au
detectability of NG effects in the comet's motion comet with NG effects strongly manifested in positional data fitting
type of model of motion GR - gravitational orbit
data weighting YES
number of residuals 1364
RMS [arcseconds] 0.40
orbit quality class 1a+
orbital elements (barycentric ecliptic J2000)
Epoch 1709 01 22
perihelion date 2009 10 07.09134030 ± 0.00027777
perihelion distance [au] 2.25547301 ± 0.00000095
eccentricity 0.99992984 ± 0.00000123
argument of perihelion [°] 2.066694 ± 0.000022
ascending node [°] 149.432123 ± 0.000016
inclination [°] 65.620451 ± 0.000004
reciprocal semi-major axis [10-6 au-1] 31.11 ± 0.54
file containing 5001 VCs swarm
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.