C/1956 R1 Arend-Roland
more info
Comet C/1956 R1 was discovered on 8 November 1956 by Sylvain Julien Victor Arend and Georges Roland (Royal Observatory, Uccle, Belgium), that is 5 months before its perihelion passage. Later, Sigeru Kaho (Tokyo Observatory, Konko Station, Japan) found an image of this comet on a plate he had exposed on 7 November 1956 during observations of variable stars. C/1956 R1 was observed until 11 April 1958 [Kronk, Cometography: Volume 4].
Comet had its closest approach to the Earth on 20 April 1957 (0.569 au), 12 days after its perihelion passage.
This is a comet with nongravitational effects strongly manifested in positional data fitting. Two NG solutions given here are based on data spanning over 0.602 yr in a range of heliocentric distances: 1.16 au – 0.778 au (perihelion) – 2.86 au; asymmetric NG solution was chosen as preffered orbit.
All solutions given here are based on data spanning over 1.42 yr in a range of heliocentric distances: 2.83 au – 0.316 au (perihelion) – 5.36 au.
This Oort spike comet suffers rather notable planetary perturbations during its passage through the planetary system; these perturbations lead to escape the comet from the planetary zone on a hyperbolic orbit (see future barycentric orbits).
See also Królikowska 2014 and Królikowska 2020.

solution description
number of observations 239
data interval 1956 11 08 – 1958 04 11
data type perihelion within the observation arc (FULL)
data arc selection entire data set (STD)
range of heliocentric distances 2.83 au – 0.32 au (perihelion) – 5.36 au
type of model of motion NT - non-gravitational orbits for asymmetric, standard g(r)
data weighting YES
number of residuals 458
RMS [arcseconds] 1.38
orbit quality class 1b
orbital elements (heliocentric ecliptic J2000)
Epoch 1956 10 14
perihelion date 1957 04 08.02761336 ± 0.00029142
perihelion distance [au] 0.31594823 ± 0.00001171
eccentricity 1.00019481 ± 0.00000835
argument of perihelion [°] 308.786869 ± 0.001307
ascending node [°] 215.856850 ± 0.000122
inclination [°] 119.939683 ± 0.000135
recip semi-major axis [10-6 au-1] -616.60 ± 26.44
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
non-gravitational parameters
A1 [10-8au\day-2] 2.4828 ± 0.2144
A2 [10-8au\day-2] 0.48596 ± 0.13095
A3 [10-8au\day-2] 0.38632 ± 0.06038
m -2.15
n 5.093
k -4.6142
r0 [au] 2.808
α 0.1113
ΔT [days] -3.0010 ± 0.866