Table 6: Comparison between two kinds of NG models for four short-period comets. NG parameters were derived from 8 of 12 detected apparitions for Comet 31P/Schwassmann-Wachmann 2, 8 of 9 detected apparitions for Comet 46P/Wirtanen (the last one were excluded), 15 of 19 apparitions for Comet 26P/Grigg-Skjellerup and all available observations (5 apparitions span over 9 perihelion passages) in the case of Comet 88P/Howell. Standard NG parameters $A_{\rm {1}}, A_{\rm {2}}, A_{\rm {3}}$ and parameter A (forced precession model) are given in units of 10-8 AU day-2. The precession factor $f_{\rm p}$ is in units of 107 day/AU, Subscript "0'' in $I_{\rm {0}}$ and $\phi _{\rm {0}}$ denotes the values for the starting epoch of integration (Epoch: 2003 12 27). For two comets (31P and 46P) the assumption about the asymmetry of function g(r) was necessary, and the time shifts $\tau $ (in days) were derived. The forced precession model of 26P was taken from Sitarski (2003).
Name Model with constant A $_{\rm {1}}, \vec{A}_{\rm {2}}$ and A $_{\rm {3}}$ Model of a rotating non-spherical nucleus
      (Forced Precession Model)
Observational arc $A_{\rm {1}}$,   $A, \eta,$  
No. of apparitions $A_{\rm {2}}$, rms $I_{\rm {0}}, \phi _{\rm {0}},$ rms
(No. of obs) $A_{\rm {3}}$   $f_{\rm p}$, s  
      $\tau $  
31P/Schwassmann-Wachmann 2 $+1.368\pm 0.026$   $+1.349\pm 0.007$, 15$^\circ$6$\pm$ 0$^\circ$2  
1955 05 22-1999 10 08 $-0.2378\pm 0.0006$ 5 $.\!\!^{\prime\prime}$21 174$^\circ$1$\pm$0$^\circ$1, 275$^\circ$1$\pm$ 7$^\circ$8 1 $.\!\!^{\prime\prime}$48
8 app (731 obs.) $-0.0628\pm 0.0452$   $+0.853\pm 0.254$, $+0.41\pm 0.02$  
      $25.7\pm 1.1$  
46P/Wirtanen $+0.971\pm 0.036$   $+0.733\pm 0.014$, 14$^\circ$0$\pm$ 1$^\circ$3  
1948 01 17-1997 12 30 $-0.1511\pm 0.0012$ 16 $.\!\!^{\prime\prime}$0 143$^\circ$1$\pm$1$^\circ$4, 314$^\circ$4$\pm$ 2$^\circ$8 1 $.\!\!^{\prime\prime}$80
8 app (214 obs.) $+0.655 \pm 0.078 $   $+0.082\pm 0.002$, $+0.32\pm 0.10$,  
      $-14.2\pm 2.1$  
88P/Howell $+0.391\pm 0.005$   $+0.364\pm 0.024$, 11$^\circ$9$\pm$ 0$^\circ$7  
1955 05 22-1999 10 08 $-0.0295\pm 0.0006$ 2 $.\!\!^{\prime\prime}$31 113$^\circ$1$\pm$2$^\circ$8, 341$^\circ$4$\pm$ 2$^\circ$8 1 $.\!\!^{\prime\prime}$19
5 app (368 obs.) $+0.0468\pm 0.0176$   $-0.129\pm 0.009$, $-0.54\pm 0.02$  
26P/Grigg-Skjellerup $-0.019\pm 0.002$   $+0.0175\pm 0.0011$, 28$^\circ$7$\pm$ 2$^\circ$2  
1922 05 18-1993 09 17 $-0.0017\pm 0.0002$ 5 $.\!\!^{\prime\prime}$05 89$^\circ$9$\pm$1$^\circ$0, 340$^\circ$7$\pm$ 3$^\circ$9 1 $.\!\!^{\prime\prime}$46
15 app (509 obs.) $-0.0012\pm 0.0055$   $-2.422\pm 0.256$, $-0.06\pm 0.07$,  


Source LaTeX | All tables | In the text