C/2015 R3 PANSTARRS
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Comet C/2015 R3 was discovered on 12 September 2015 with Pan-STARRS 1 telescope (Haleakala), that is about 1.6 yr after its perihelion passage. After some time pre-discovery data were found going back to 5 March 2013. This comet was rarely observed until 28 September 2016.

Comet had its closest approach to the Earth on 8 May 2015 (4.939 au), a week after its perihelion passage.

We recommended GR solution spanning over 3.57 yr in a range of heliocentric distances from 5.57 au – 4.90 au (perihelion) – 8.54 au as the preferred orbit( solution 'b1'), because radial component of NG~acceleration is negative in solution 'bc'.

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 larger than 10000 au (see future barycentric orbits).
solution description
number of observations 36
data interval 2015 09 12 – 2016 09 28
data arc selection data generally limited to post-perihelion (POS)
range of heliocentric distances 6.56 au – 8.54au
detectability of NG effects in the comet's motion comet with determinable NG~orbit
type of model of motion GR - gravitational orbit
data weighting YES
number of residuals 65
RMS [arcseconds] 0.46
orbit quality class 1b
orbital elements (heliocentric ecliptic J2000)
Epoch 2014 02 12
perihelion date 2014 02 11.76181393 ± 0.01324740
perihelion distance [au] 4.90324280 ± 0.00009957
eccentricity 0.99841764 ± 0.00005607
argument of perihelion [°] 272.008279 ± 0.001127
ascending node [°] 36.429668 ± 0.000117
inclination [°] 83.599006 ± 0.000275
reciprocal semi-major axis [10-6 au-1] 322.72 ± 11.43
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.