C/2009 O4 Hill
more info
Comet C/2009 O4 was discovered on 30 July 2009 by R. E. Hill (Catalina Sky Survey); that is about 5 months before its perihelion passage. The comet was observed only before perihelion until 14 December 2009.
Comet had its closest approach to the Earth on 19 September 2009 (1.819 au), about 1.5 month after its discovery.
Solution given here is based on data spanning over 0.375 yr in a narrow range of heliocentric distances from 3.04 au to 2.57 au.
This Oort spike comet suffers small planetary perturbations during its passage through the planetary system; however, these perturbations lead to escape the comet from the solar system on hyperbolic orbit (see future barycentric orbits).
See also Królikowska and Dybczyński 2013 and Królikowska 2020.

solution description
number of observations 785
data interval 2009 07 30 – 2009 12 14
data type observed only before perihelion (PRE)
data arc selection entire data set (STD)
range of heliocentric distances 3.04 au – 2.57au
detectability of NG effects in the comet's motion NG effects not determinable
type of model of motion GR - gravitational orbit
data weighting YES
number of residuals 1522
RMS [arcseconds] 0.39
orbit quality class 1b
orbital elements (barycentric ecliptic J2000)
Epoch 1708 06 30
perihelion date 2009 12 31.71873840 ± 0.00101094
perihelion distance [au] 2.55680478 ± 0.00000794
eccentricity 0.99985692 ± 0.00001255
argument of perihelion [°] 223.896771 ± 0.000350
ascending node [°] 172.974938 ± 0.000027
inclination [°] 95.832953 ± 0.000156
recip semi-major axis [10-6 au-1] 55.96 ± 4.91
file containing 5001 VCs swarm
2009o4a5.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.