C/2015 O1 PANSTARRS
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Comet C/2015 O1 was discovered on 19 July 2015 with Pan-STARRS 1 telescope (Haleakala), that is about  months after its perihelion passage.

Some prediscovery images of this comet were found: taken on 15 and 17 of June 2015 by Space Surveillance Telescope (Atom Site).

Solutions given here are based on data spanning over 4.76 yr in a range of heliocentric distances: 8.65 au – 3.730 au (perihelion) – 7.28 au.

NG orbits using full data-arc as well as independently using pre-perihelion and post-perihelion data are determinable.

See also Królikowska and Dones 2023.
solution description
number of observations 4142
data interval 2015 06 15 – 2020 03 20
data type perihelion within the observation arc (FULL)
data arc selection entire data set (STD)
range of heliocentric distances 8.65 au – 3.73 au (perihelion) – 7.28 au
type of model of motion NH - non-gravitational orbits for water sublimation from subsolar point
data weighting YES
number of residuals 8242
RMS [arcseconds] 0.48
orbit quality class 1a+
orbital elements (barycentric ecliptic J2000)
Epoch 1714 10 03
perihelion date 2018 02 18.04416872 ± 0.00020416
perihelion distance [au] 3.72111134 ± 0.00000143
eccentricity 0.99984586 ± 0.00000150
argument of perihelion [°] 89.693769 ± 0.000041
ascending node [°] 299.871810 ± 0.000008
inclination [°] 127.176613 ± 0.000005
reciprocal semi-major axis [10-6 au-1] 41.42 ± 0.40
file containing 5001 VCs swarm
2015o1bs.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.