Solar System
Dynamics &
Planetology
Group 		C/1991 F2 Helin–Lawrence


SSDP Cometary Note C1991F2N1-001

Comet C/1991 F2 Helin–Lawrence

number of observations 114
number of residuals 213
data interval 1991 Feb. 23 — 1992 Sep. 30
rms [arcsec] 0.78
orbit quality class 1b

Osculating orbital elements (heliocentric; ecliptic J2000.0)

Epoch (TT) 19920119.0 = JD 2448640.5
time of perihelion passage (TT) 19920120.026976 ± 0.000122
perihelion distance 1.51771129 ± 0.00000327
eccentricity 1.00040745 ± 0.00000888
argument of perihelion [deg] 271.159246 ± 0.000035
longitude of the ascending node [deg] 11.834904 ± 0.000028
inclination [deg] 95.456595 ± 0.000089
inverse semimajor axis [10-6 au-1] -268.47 ± 5.85

Nongravitational parameters [10-8 au/day2] A1 = 0.656 ± 0.230 A2 = -0.340 ± 0.134 A3 = 0.0724 ± 0.0379

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) 16921106
time of perihelion passage (TT) 19920118.919635 ± 0.000253
perihelion distance 1.51348314 ± 0.00000532
eccentricity 0.99997844 ± 0.00000609
argument of perihelion [deg] 271.252214 ± 0.000271
longitude of the ascending node [deg] 11.832361 ± 0.000025
inclination [deg] 95.452472 ± 0.000085
inverse semimajor axis [10-6 au-1] 14.24 ± 4.03

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) 22900116
time of perihelion passage (TT) 19920120.599324 ± 0.000348
perihelion distance 1.51751230 ± 0.00000604
eccentricity 1.00014135 ± 0.00001110
argument of perihelion [deg] 271.120029 ± 0.000370
longitude of the ascending node [deg] 11.863681 ± 0.000048
inclination [deg] 95.430183 ± 0.000085
inverse semimajor axis [10-6 au-1] -93.14 ± 7.31


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.





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