C/2015 X7 ATLAS
more info
Comet C/2015 X7 was discovered on 12 December 2015 by Asteroid Terrestrial-impact Last Alert System (ATLAS) Team, that is about 7.5 months before its perihelion passage. Some prediscovery images of this comet were found: taken on 28 January 2015 by Pan-STARRS 1, Haleakala. This comet was observed until 16 June 2017.
Comet had its closest approach to the Earth on 8 February 2017 (5.909 au); about 6 months after its perihelion passage.
Solutions given here are based on data spanning over 2.38 yr in a range of heliocentric distances: 5.95 au – 3.685 au (perihelion) – 4.64 au.
This Oort spike comet suffers small planetary perturbations during its passage through the planetary system that lead to a more tight future orbit with a semimajor axis of about 5,000 au (see future barycentric orbits).

solution description
number of observations 628
data interval 2015 01 28 – 2017 06 16
data type perihelion within the observation arc (FULL)
data arc selection entire data set (STD)
range of heliocentric distances 5.95 au – 3.69 au (perihelion) – 4.64 au
type of model of motion NC - non-gravitational orbits for symmetric CO-g(r)-like function
data weighting YES
number of residuals 1244
RMS [arcseconds] 0.43
orbit quality class 1a+
next orbit statistics, both Galactic and stellar perturbations were taken into account
no. of returning VCs in the swarm 5001 *
no. of escaping VCs in the swarm 0
no. of hyperbolas among escaping VCs in the swarm 0
next reciprocal semi-major axis [10-6 au-1] 196.88 – 200.01 – 203.19
next perihelion distance [au] 3.659 – 3.6602 – 3.6614
next aphelion distance [103 au] 9.84 – 10 – 10.2
time interval to next perihelion [Myr] 0.345 – 0.353 – 0.361
percentage of VCs with qnext < 10100
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.
next orbit statistics, here only the Galactic tide has been included
no. of returning VCs in the swarm 5001 *
no. of escaping VCs in the swarm 0
no. of hyperbolas among escaping VCs in the swarm 0
next reciprocal semi-major axis [10-6 au-1] 196.88 – 200.01 – 203.19
next perihelion distance [au] 3.6552 – 3.6564 – 3.6576
next aphelion distance [103 au] 9.84 – 10 – 10.2
time interval to next perihelion [Myr] 0.345 – 0.353 – 0.361
percentage of VCs with qnext < 10100