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+
previous 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
previous reciprocal semi-major axis [10-6 au-1] 28.02 – 30.47 – 32.91
previous perihelion distance [au] 1700 – 2000 – 2400
previous aphelion distance [103 au] 59.1 – 63.6 – 69
time interval to previous perihelion [Myr] 5 – 5.7 – 6.5
percentage of VCs with qprev > 20100
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.
previous 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
previous reciprocal semi-major axis [10-6 au-1] 28.30 – 30.95 – 33.61
previous perihelion distance [au] 27 – 40 – 64
previous aphelion distance [103 au] 59.5 – 64.6 – 70.6
time interval to previous perihelion [Myr] 5.1 – 5.8 – 6.6
percentage of VCs with 10 < qprev < 201
percentage of VCs with qprev > 2099