C/2017 M4 ATLAS
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Comet C/2017 M4 was discovered on 21 June 2017 by Asteroid Terrestrial-impact Last Alert System (ATLAS) Team, that is about  months after its perihelion passage.

Some prediscovery images of this comet were found: taken on 16 June 2017 by Pan-STARRS 1 telescope (Haleakala).

Solutions given here are based on data spanning over 4.46 yr in a range of heliocentric distances: 6.09 au – 3.252 au (perihelion) – 9.19 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 3284
data interval 2017 06 16 – 2021 11 30
data type perihelion within the observation arc (FULL)
data arc selection entire data set (STD)
range of heliocentric distances 6.09 au – 3.25 au (perihelion) – 9.19 au
type of model of motion NH - non-gravitational orbits for water sublimation from subsolar point
data weighting YES
number of residuals 6492
RMS [arcseconds] 0.47
orbit quality class 1a+
orbital elements (barycentric ecliptic J2000)
Epoch 1716 05 25
perihelion date 2019 01 18.65282342 ± 0.00016713
perihelion distance [au] 3.24469692 ± 0.00000117
eccentricity 0.99983510 ± 0.00000150
argument of perihelion [°] 167.764649 ± 0.000034
ascending node [°] 65.816137 ± 0.000008
inclination [°] 105.658071 ± 0.000004
reciprocal semi-major axis [10-6 au-1] 50.82 ± 0.46
file containing 5001 VCs swarm
2017m4st.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.