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Comet C/2016 A1 was discovered on 1 January 2016 with Pan-STARRS 1 telescope (Haleakala), that is about almost 2 yr before its perihelion passage, and was next observed until 15 February 2020.

Comet had its closest approach to the Earth on 17 January 2018 (4.397 au); about 2 months after its perihelion passage.

Solutions given here are based on data spanning over 4.12 yr in a range of heliocentric distances: 7.31 au    5.328 au (perihelion) – 7.90 au.

This Oort spike comet suffers small planetary perturbations during its passage through the planetary system that lead to a more tight future orbit (see future barycentric orbit).

See also Królikowska and Dones 2023.

solution description
number of observations 1648
data interval 2016 01 01 – 2018 05 17
data arc selection data generally limited to pre-perihelion (PRE)
range of heliocentric distances 7.31 au – 5.33 au (perihelion) – 5.49 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 3216
RMS [arcseconds] 0.45
orbit quality class 1a+
orbital elements (heliocentric ecliptic J2000)
Epoch 2017 11 23
perihelion date 2017 11 23.37173396 ± 0.00028273
perihelion distance [au] 5.32776441 ± 0.00000153
eccentricity 1.00198561 ± 0.00000178
argument of perihelion [°] 10.320260 ± 0.000030
ascending node [°] 128.174520 ± 0.000003
inclination [°] 121.185724 ± 0.000005
reciprocal semi-major axis [10-6 au-1] -372.69 ± 0.33
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).