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 (barycentric ecliptic J2000)
Epoch 2247 11 18
perihelion date 1957 04 08.42811259 ± 0.00009367
perihelion distance [au] 0.31298222 ± 0.00000258
eccentricity 1.00018361 ± 0.00000363
argument of perihelion [°] 308.814834 ± 0.000356
ascending node [°] 216.076681 ± 0.000087
inclination [°] 119.9013 ± 0.00006
reciprocal semi-major axis [10-6 au-1] -586.64 ± 11.60
file containing 5001 VCs swarm
1956r1n3.bpl
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.
Six 2D-projections of the 6D space of future swarm including 5001 VCs. Each density map is given in logarithmic scale presented on the right in the individual panel.