Solar System
Dynamics &
Planetology
Group 		C/2008 A1 McNaught


General description

data set of C/2008 A1
Trends in the O-C time variations even for asymmetric non-gravitational solutions based on entire data set (SSDP Cometary Note C2008A1N6-001, see just below) were noticed; O-C time variations of non-gravitational solution in comparison to O-C variation for pure GR solution are shown in the figure on the right. Due to its erratic behaviour, this comet should be examined in a special way and two dedicated separate non-gravitational orbits were determined (recommended for backward and forward dynamical studies, respectively).

Thus, here two types of solutions are given: This second type of solutions is recommended for studying the dynamical evolution of this comet.
More details in Królikowska and Dybczyński, 2013.


Figure caption: 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 lines show the perihelion distance for a given comet whereas vertical dotted lines — the moment of perihelion passage. Middle panel: O-C diagram for the non-gravitational solution shows some trends in right ascension (magenta dots) and declination (blue open circles). Lowest panel: O-C time vatiations for gravitational solution shows strong influence of the non-gravitational effects on the motion of this comet. The same figure in the new window



SSDP Cometary Note C2008A1N6-001

Comet C/2008 A1 McNaught (asymmetric non-gravitational solution)

number of observations 937
number of residuals 1852
data interval 2008 Jan. 10 — 2010 Jan. 17
rms [arcsec] 0.44
orbit quality class 1a

Osculating orbital elements (heliocentric; ecliptic J2000.0)

Epoch (TT) 20080911.0 = JD 2454720.5
time of perihelion passage (TT) 20080929.127602 ± 0.000067
perihelion distance 1.07306392 ± 0.00000067
eccentricity 1.00018943 ± 0.00000225
argument of perihelion[deg] 348.477291 ± 0.000083
longitude of the ascending node [deg] 277.883733 ± 0.000026
inclination[deg] 82.549129 ± 0.000012
inverse semimajor axis [10-6 au-1] -176.53 ± 2.10

Nongravitational parameters [10-8 au/day2] A1 = 5.5964 ± 0.0570 A2 = 0.7136 ± 0.0384 A3 = 0.16800 ± 0.00815
time shift of g(r) relative to perihelion [day] 5.76 ± 0.6

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

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

Epoch (TT) 17090122.0
time of perihelion passage (TT) 20080929.788657 ± 0.000061
perihelion distance 1.07272957 ± 0.00000096
eccentricity 0.99986798 ± 0.00000161
argument of perihelion[deg] 348.519718 ± 0.000054
longitude of the ascending node [deg] 277.853954 ± 0.000024
inclination[deg] 82.555262 ± 0.000013
inverse semimajor axis [10-6 au-1] 123.07 ± 1.50

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.

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

Epoch (TT) 23091223.0
time of perihelion passage (TT) 20080929.205406 ± 0.000085
perihelion distance 1.06958685 ± 0.00000305
eccentricity 0.99972575 ± 0.00000239
argument of perihelion[deg] 348.352122 ± 0.000179
longitude of the ascending node [deg] 277.900996 ± 0.000025
inclination[deg] 82.577603 ± 0.000017
inverse semimajor axis [10-6 au-1] 256.41 ± 2.24


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.




SSDP Cometary Note C2008A1P5-001

Comet C/2008 A1 McNaught (non-gravitational solution based on pre-perihelion data)

number of observations 393
number of residuals 770
data interval 2008 Jan. 10 — 2008 Sep. 28 (pre-perihelion data)
rms [arcsec] 0.28
orbit quality class 1b

Osculating orbital elements (heliocentric; ecliptic J2000.0)

Epoch (TT) 20080911.0 = JD 2454720.5
time of perihelion passage (TT) 20080929.125802 ± 0.000332
perihelion distance 1.07308711 ± 0.00000375
eccentricity 1.00026451 ± 0.00001289
argument of perihelion[deg] 348.474897 ± 0.000437
longitude of the ascending node [deg] 277.882018 ± 0.000212
inclination[deg] 82.550006 ± 0.000100
inverse semimajor axis [10-6 au-1] -246.50 ± 12.01

Nongravitational parameters [10-8 au/day2] A1 = 4.608 ± 0.136 A2 = 1.894 ± 0.233 A3 = 1.844 ± 0.203

Note: Epoch is given in a format: yyyymmdd.d, time of perihelion passage in a format of yyyymmdd.dddddd.
Most recommended model for studying the origin of this comet.

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

Epoch (TT) 17090122.0
time of perihelion passage (TT) 20080929.789350 ± 0.000230
perihelion distance 1.07273156 ± 0.00000106
eccentricity 0.99987037 ± 0.00000218
argument of perihelion[deg] 348.519683 ± 0.000072
longitude of the ascending node [deg] 277.854140 ± 0.000024
inclination[deg] 82.555436 ± 0.000021
inverse semimajor axis [10-6 au-1] 120.84 ± 2.03

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




SSDP Cometary Note C2008A1R5-001

Comet C/2008 A1 McNaught (non-gravitational solution based on post-perihelion data)

number of observations 544
number of residuals 1072
data interval 2008 Oct. 1 — 2010 Jan. 17 (post-perihelion data)
rms [arcsec] 0.54
orbit quality class 1b

Osculating orbital elements (heliocentric; ecliptic J2000.0)

Epoch (TT) 20080911.0 = JD 2454720.5
time of perihelion passage (TT) 20080929.124280 ± 0.000432
perihelion distance 1.07294448 ± 0.00000714
eccentricity 0.99955656 ± 0.00003447
argument of perihelion[deg] 348.472703 ± 0.000583
longitude of the ascending node [deg] 277.886946 ± 0.000197
inclination[deg] 82.556261 ± 0.000473
inverse semimajor axis [10-6 au-1] 413.30 ± 32.12

Nongravitational parameters [10-8 au/day2] A1 = 10.094 ± 0.282 A2 = 6.142 ± 0.291 A3 = -4.431 ± 0.306

Note: Epoch is given in a format: yyyymmdd.d, time of perihelion passage in a format of yyyymmdd.dddddd.
Most recommended model for studying the future evolution of this comet.

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

Epoch (TT) 23091113.0
time of perihelion passage (TT) 20080929.208570 ± 0.000181
perihelion distance 1.06952611 ± 0.00000546
eccentricity 0.99973634 ± 0.00000302
argument of perihelion[deg] 348.350303 ± 0.000270
longitude of the ascending node [deg] 277.900870 ± 0.000048
inclination[deg] 82.577708 ± 0.000016
inverse semimajor axis [10-6 au-1] 246.52 ± 2.82

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

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, 2013. All rights reserved

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