Solar System
Dynamics &
Planetology
Group 		C/1946 U1 Bester



General description

data set of C/1946 U1

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Comet C/1946 U1 was discovered on 31 October 1946, that is over three months before perihelion passage, and was last seen on 2 October 1948 [Kronk, Cometography: Volume 4].

This comet made its closest approach to the Earth on 29 November 1946 (1.864 au), that is about one month after its discovery.

Solution given below is based on data span over 1.918 yr in a range of heliocentric distances from 2.631 au through perihelion (2.408 au) to 6.316 au.

Pure gravitational orbit determined from all available positional measurements (141 observations) give slightly hyperbolic original barycentric orbit (1a-class orbit); also original orbit given in Minor Planet Center is slightly hyperbolic (97 obs. used, the same arc of data; 1A-class orbit, see MPC).

It was possible to determine the non-gravitational orbit for C/1946 U1 where a small decrease of RMS was obtained (from 1.25 arcsec to 1.18 arcsec, see below). This NG-solution give elliptical original orbit (see original barycentric orbits given below).

Comet suffered slight (pure gravitational solution) or small (NG solution) planetary perturbations during its passage through the planetary system. According to both solutions, hovever, it will enter the planet zone as Oort spike comet in the next perihelion passage (see future barycentric orbits given below).

More details in Królikowska et al. 2014


Figure caption: 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 orbit — see below SSDP Cometary Note C1946U1N5-001

SSDP Cometary Note C1946U1A5-001

Comet C/1946 U1 Bester

number of observations 141
number of residuals 259
data interval 1946 Nov. 2 — 1948 Oct. 2
rms [arcsec] 1.25
orbit quality class 1a

Osculating orbital elements (heliocentric; ecliptic J2000.0)

Epoch (TT) 19470224.0 = JD 2432240.5
time of perihelion passage (TT) 19470207.362613 ± 0.000422
perihelion distance 2.40766593 ± 0.00000218
eccentricity 1.00094633 ± 0.00001085
argument of perihelion [deg] 348.624706 ± 0.000140
longitude of the ascending node [deg] 35.558527 ± 0.000049
inclination [deg] 108.174444 ± 0.000048
inverse semimajor axis [10-6 au-1] -393.05 ± 4.50

Note: Epoch is given in a format: yyyymmdd.d, time of perihelion passage in a format of yyyymmdd.dddddd.



data set of C/1946 U1

Figure caption: Six 2D-projections of the 6D space of original swarm (5001 VCs) of C/1946 U1. Each density map is given in logarithmic scale presented on the right in the individual panel.
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Original orbital elements (barycentric; at 250 au from the Sun)

Epoch (TT) 16460601
time of perihelion passage (TT) 19470206.851120 ± 0.000554
perihelion distance 2.41089055 ± 0.00000216
eccentricity 1.00000141 ± 0.00001094
argument of perihelion [deg] 348.604392 ± 0.000140
longitude of the ascending node [deg] 35.566639 ± 0.000048
inclination [deg] 108.115380 ± 0.000048
inverse semimajor axis [10-6 au-1] -0.59 ± 4.54

Note: Values of uncertainties of original/future orbital elements were derived using a swarm of 5001 osculating orbits of VCs (including the nominal osculating orbit given above) for original/future orbital evolution calclulations and then by fitting the distribution of a given orbital element of original/future swarm of VCs to Gaussian distribution.

Original barycentric positions and velocities of 5001 VCs at 250 au from the Sun are given here   (data format), i.e. before entering the planetary zone.



data set of C/1946 U1

Figure caption: Six 2D-projections of the 6D space of future swarm (5001 VCs) of C/1946 U1. Each density map is given in logarithmic scale presented on the right in the individual panel.
The same figure in the new window

Future orbital elements (barycentric; at 250 au from the Sun)

Epoch (TT) 22471228
time of perihelion passage (TT) 19470207.503759 ± 0.000434
perihelion distance 2.41255932 ± 0.00000210
eccentricity 0.99993675 ± 0.00001094
argument of perihelion [deg] 348.625816 ± 0.000140
longitude of the ascending node [deg] 35.533705 ± 0.000048
inclination [deg] 108.158906 ± 0.000048
inverse semimajor axis [10-6 au-1] 26.22 ± 4.54


Future barycentric positions and velocities of 5001 VCs at 250 au from the Sun are given here   (data format), i.e. after leaving the planetary zone.



Non–gravitational orbit


SSDP Cometary Note C1946U1N5-001

number of observations 141
number of residuals 260
data interval 1946 Nov. 2 — 1948 Oct. 2
rms [arcsec] 1.18
orbit quality class 1b

Osculating orbital elements (heliocentric; ecliptic J2000.0)

Epoch (TT) 19470224.0 = JD 2432240.5
time of perihelion passage (TT) 19470207.359379 ± 0.000829
perihelion distance 2.40760977 ± 0.00000832
eccentricity 1.00078508 ± 0.00002276
argument of perihelion [deg] 348.623288 ± 0.000323
longitude of the ascending node [deg] 35.559084 ± 0.000076
inclination [deg] 108.174491 ± 0.000052
inverse semimajor axis [10-6 au-1] -326.08 ± 9.45

Nongravitational parameters [10-8 au/day2] A1 = 18.522 ± 4.308 A2 = 33.548 ± 4.813 A3 = 0.0 (assumed)

Note: Epoch is given in a format: yyyymmdd.d, time of perihelion passage in a format of yyyymmdd.dddddd.



data set of C/1946 U1

Figure caption: Six 2D-projections of the 6D space of original swarm (5001 VCs) of C/1946 U1. Each density map is given in logarithmic scale presented on the right in the individual panel.
The same figure in the new window

Original orbital elements (barycentric; at 250 au from the Sun)

Epoch (TT) 16440830
time of perihelion passage (TT) 19470206.867800 ± 0.002738
perihelion distance 2.41079026 ± 0.00001452
eccentricity 0.99962333 ± 0.00005035
argument of perihelion [deg] 348.609407 ± 0.000996
longitude of the ascending node [deg] 35.567221 ± 0.000079
inclination [deg] 108.115436 ± 0.000053
inverse semimajor axis [10-6 au-1] 156.24 ± 20.88

Note: Values of uncertainties of original/future orbital elements were derived using a swarm of 5001 osculating orbits of VCs (including the nominal osculating orbit given above) for original/future orbital evolution calclulations and then by fitting the distribution of a given orbital element of original/future swarm of VCs to Gaussian distribution.

Original barycentric positions and velocities of 5001 VCs at 250 au from the Sun are given here   (data format), i.e. before entering the planetary zone.



data set of C/1946 U1

Figure caption: Six 2D-projections of the 6D space of future swarm (5001 VCs) of C/1946 U1. Each density map is given in logarithmic scale presented on the right in the individual panel.
The same figure in the new window

Future orbital elements (barycentric; at 250 au from the Sun)

Epoch (TT) 22471228
time of perihelion passage (TT) 19470207.504905 ± 0.001239
perihelion distance 2.41250381 ± 0.00001204
eccentricity 0.99995116 ± 0.00001494
argument of perihelion [deg] 348.624898 ± 0.000455
longitude of the ascending node [deg] 35.534261 ± 0.000076
inclination [deg] 108.158955 ± 0.000052
inverse semimajor axis [10-6 au-1] 20.24 ± 6.19


Future barycentric positions and velocities of 5001 VCs at 250 au from the Sun are given here   (data format), i.e. after leaving the planetary zone.





Solar System Dynamics & Planetology Group, 2014. All rights reserved

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