C/2015 K4 PanSTARRS
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Comet C/2015 K4 was discovered on 24 May 2015 by Pan-STARRS 1, Haleakala, that is about three weeks after its perihelion passage. Comet was observed for less than two months until 14 July 2015. C/2015 K4 had closest approach to the Earth on 25 May 2015 (1.061 au, 3.5 weeks after the perihelion passage).

This is a comet with a short data arc and we show here two GR solutions differing in data treatment: 'a5' (data were weighting) and 'a1' (weighting procedure was omitted); bothare based on data spanning over 0.14 yr in a narrow range of heliocentric distances from 2.03 au to 2.20 au.

According to both GR solutions, original semimajor axis of C/2015 K4 is about 1100–1800 au (uncertainty of one sigma was included). Due to moderate planetary perturbations, its future orbit will be much looser; it is uncertain whether this comet will leave the solar system in a hyperbolic orbit.
solution description
number of observations 134
data interval 2015 05 24 – 2015 07 14
data type observed only after perihelion (POST)
data arc selection entire data set (STD)
range of heliocentric distances 2.03 au – 2.2au
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 259
RMS [arcseconds] 0.35
orbit quality class 2b
next orbit statistics, both Galactic and stellar perturbations were taken into account
no. of returning VCs in the swarm 1242
no. of escaping VCs in the swarm 3759
no. of hyperbolas among escaping VCs in the swarm 3489 *
next reciprocal semi-major axis [10-6 au-1] -205.37 – -60.82 – 87.45
next perihelion distance [au] 2 – 2.7 – 13 R
next aphelion distance [103 au] 13 – 35 – 210
time interval to next perihelion [Myr] 0.46 – 1.7 – 7.5 R
percentage of VCs with qnext < 1069
percentage of VCs with 10 < qnext < 2024
percentage of VCs with qnext > 207
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).
next_g orbit statistics, here only the Galactic tide has been included
no. of returning VCs in the swarm 1257
no. of escaping VCs in the swarm 3744
no. of hyperbolas among escaping VCs in the swarm 3489 *
next reciprocal semi-major axis [10-6 au-1] -205.43 – -60.87 – 87.42
next perihelion distance [au] 1.82 – 1.99 – 29.6 R
next aphelion distance [103 au] 13 – 35 – 210
time interval to next perihelion [Myr] 0.46 – 1.7 – 7.8 R
percentage of VCs with qnext < 1086
percentage of VCs with 10 < qnext < 202
percentage of VCs with qnext > 2012