C/2015 XY1 Lemmon
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Comet C/2015 XY1 was discovered on 4 December 2015 with Mount Lemmon survey, that is about 2.4 yr before its perihelion passage, and was observed until 1 January 2020.

Comet had its closest approach to the Earth on 27 December 2017 (6.984 au); about 4 months before its perihelion passage.

Solutions given here are based on data spanning over 4.88 yr in a range of heliocentric distances from 9.52 au     7.928 au (perihelion) – 9.62 au.

This Oort spike comet suffers slight planetary perturbations during its passage through the planetary system; however, these perturbations can lead to escape the comet from the planetary zone on a marginally hyperbolic orbit (see future barycentric orbit for solution ra).

See also Królikowska and Dones 2023.
solution description
number of observations 738
data interval 2015 12 04 – 2020 01 01
data type perihelion within the observation arc (FULL)
data arc selection entire data set (STD)
range of heliocentric distances 9.52 au – 7.93 au (perihelion) – 9.62 au
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 1439
RMS [arcseconds] 0.51
orbit quality class 1a+
orbital elements (barycentric ecliptic J2000)
Epoch 1707 11 09
perihelion date 2018 04 29.17122067 ± 0.00084506
perihelion distance [au] 7.93546080 ± 0.00000528
eccentricity 0.99976139 ± 0.00000458
argument of perihelion [°] 196.231405 ± 0.000048
ascending node [°] 281.553736 ± 0.000010
inclination [°] 148.842055 ± 0.00001
reciprocal semi-major axis [10-6 au-1] 30.07 ± 0.58
file containing 5001 VCs swarm
2015xyba.bmi
Upper panel: 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.
Middle panel(s): O-C diagram for a given solution (sometimes in comparison to another solution available in CODE), where residuals in right ascension are shown using magenta dots and in declination by blue open circles.
Lowest panel: Relative weights for a given data set(s).
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.