OAA computing section circular NK 729 2P/Encke
The following improved orbital elements, by S. Nakano, are from 254 observations 1986-1999, including planetary perturbations by Mercury to Neptune and three minor planets, Ceres, Pallas, Vesta, and non-gravitational effect of style II. The mean residual is +/- 0.78 arc second. See previous computations on NKs 485 (1985), 519 (1987), 545 (1990), 618 (1994), 658 (1997) and 719 (1999). Epoch = 2000 Sept.13.0 TT T = 2000 Sept. 9.66663 +/- 0.00012 (m.e.) TT Peri. = 186.48354 +/- 0.00006 Node = 334.60004 +/- 0.00005 (2000.0) Inc. = 11.75546 +/- 0.00001 q = 0.3395375 +/- 0.0000002 AU e = 0.8468987 +/- 0.0000002 a = 2.2177309 +/- 0.0000011 AU n' = 0.29842884 +/- 0.00000023 P = 3.303 +/- 0.0000025 years A1 = -0.010 +/- 0.003 A2 = -0.00122 +/- 0.00002 T = 1987 July 17.40130 TT Epoch = 1987 July 24.0 TT Peri. = 186.25359 e = 0.8498912 Node = 334.73987 (2000.0) a = 2.2099589 AU Inc. = 11.93118 n'= 0.30000450 q = 0.3317344 AU P = 3.285 years T = 1990 Oct. 28.56741 TT Epoch = 1990 Nov. 5.0 TT Peri. = 186.23539 e = 0.8502196 Node = 334.74857 (2000.0) a = 2.2091714 AU Inc. = 11.94480 n'= 0.30016494 q = 0.3308905 AU P = 3.284 years T = 1994 Feb. 9.47840 TT Epoch = 1994 Feb. 17.0 TT Peri. = 186.27166 e = 0.8502115 Node = 334.72798 (2000.0) a = 2.2092293 AU Inc. = 11.94013 n'= 0.30015313 q = 0.3309172 AU P = 3.284 years T = 1997 May 23.59865 TT Epoch = 1997 June 1.0 TT Peri. = 186.27263 e = 0.8500136 Node = 334.72088 (2000.0) a = 2.2095067 AU Inc. = 11.92937 n'= 0.30009662 q = 0.3313960 AU P = 3.284 years The predicted orbit for the 2003 return is as follows: T = 2003 Dec. 29.87649 TT Epoch = 2003 Dec. 27.0 TT Peri. = 186.49866 e = 0.8473402 Node = 334.58759 (2000.0) a = 2.2170982 AU Inc. = 11.76959 n'= 0.29855660 q = 0.3384617 AU P = 3.301 years The following residuals in seconds of arc are from the above orbital elements: 1986/ 931207 360 0.2+ 0.1- 961004 691 0.4+ 0.0 860831 691 0.9+ 1.9- 931208 691 0.1- 0.1+ 961005 360 0.3+ 0.7+ 860831 691 0.5+ 0.9- 931208 691 0.1+ 0.0 961005 360 0.5+ 0.5+ 860831 691 0.3+ 0.9- 931208 691 0.2- 0.2+ 961012 691 (3.9+ 0.3-) 860901 691 0.8- 1.7- 931208 360 1.0- 0.1- 961012 691 0.2+ 0.0 860901 691 0.5- 0.7- 931208 360 0.9- 0.1+ 961012 691 0.2+ 0.5+ 860902 691 0.0 1.2- 931211 107 (2.6- 0.4+) 961012 118 0.4+ 0.6+ 860902 691 0.0 1.1- 931211 107 0.6- 1.6+ 961012 118 0.7+ 0.4+ 860902 691 0.5+ 1.4- 931212 107 0.7- 2.2+ 961016 360 0.4- 0.1+ 860925 691 0.7+ 1.8- 931214 897 (5.2- 1.5+) 961016 360 0.6- 0.5- 860925 691 0.7+ 1.4- 931214 897 (5.5- 2.6+) 961103 118 1.3+ 0.7+ 860926 691 0.0 0.3- 931216 107 0.4+ 0.1+ 961103 118 1.0+ 0.9+ 860926 691 0.6- 0.3+ 931216 107 1.0+ 0.1+ 961104 118 1.5+ 0.6+ 860926 691 0.9- 0.1+ 931217 897 (6.4- 0.2-) 961104 118 1.6+ 0.6+ 1987/ 931217 897 (7.8- 0.6+) 961228 360 0.6+ 1.0+ 870813 474 (3.3- 0.9-) 931217 897 (8.0- 2.2+) 961228 360 0.1+ 0.6+ 870813 474 0.8- 2.2- 931217 107 0.6+ 1.4+ 961230 867 0.4+ 0.2- 870815 323 1.6+ 0.3- 931217 107 1.3- 0.1+ 961230 867 0.7+ 0.2- 870817 323 1.7- 0.9- 931223 107 1.6- 0.7- 961230 867 0.8+ 1.2+ 870818 323 (3.6- 2.8-) 931224 897 (7.5- 3.9+)Y 1997/ 870819 474 (5.3+ 3.3-) 931224 897(11.1- 2.1+)Y 970604 422 (2.4- 1.9-) 870819 474 0.7- 0.3- 931227 897 (3.8- 2.0+) 970604 422 (0.2- 3.0-) 1988/ 931227 897 (5.9- 1.4+) 970605 422 (0.9- 2.8-) 880517 568 (3.7+ 0.5-) 931227 107 (3.7- 1.7+) 970605 422 (0.1+ 3.0-) 880518 568 1.9+ 0.6+ 931227 107 (3.8- 3.1+) 970608 422 (3.9- 3.3-) 880909 568 (2.3+ 0.2-) 931228 107 (4.4- 1.3-) 970623 422 (3.2- 3.0-) 880909 568 (3.0+ 0.4+) 931228 107 (6.5- 1.9+) 970624 422 0.7- 0.9- 880909 568 (2.4+ 0.1+) 1994/ 970624 422 (2.2+ 2.4+) 880909 568 (3.3+ 0.8+) 940102 410 (4.6- 1.9+) 970624 422 0.5- 1.2- 880909 568 (3.8+ 0.6+) 940102 410 0.6+ 0.1- 970624 422 0.4- 0.4- 880909 568 (5.1+ 1.3+) 940104 887 0.5- 0.0 970626 422 (3.2- 0.2+) 880911 568 0.1- 0.6+ 940104 887 0.6- 0.2- 970627 422 1.9- 1.9+ 880911 568 0.6+ 0.1+ 940105 691 0.3+ 0.2+ 970627 422 2.2- 0.7- 880912 568 0.1+ 1.3+ 940105 691 0.2- 0.2+ 970627 422 0.4- 0.1- 880912 568 0.2- 1.5+ 940107 897 (3.6- 2.3+) 970627 422 0.4- 0.8+ 880912 568 (1.0- 2.5+) 940107 897 (3.1- 2.4+) 970627 422 (3.8- 1.1-) 1989/ 940109 360 0.7- 1.1+ 970627 422 (2.9- 1.4+) 890601 568 1.8+ 1.0- 940109 360 1.4- 1.1+ 970628 422 0.6+ 0.9+ 890601 568 0.9+ 1.3- 940109 605 (7.4- 2.9+) 970628 422 2.0- 1.0- 890602 568 0.2- 0.9+ 940109 605 (8.4- 1.2+) 970628 422 0.6- 1.5+ 890602 568 0.0 0.3- 940109 605 (6.6- 4.0+) 970628 422 (2.6- 1.3+) 890602 568 0.1- 0.3+ 940112 107 (7.8- 3.2+) 970701 422 1.0- 0.6- 890801 568 0.1+ 0.4- 940113 107 (6.2- 2.8+) 970701 422 0.6- 0.7- 890801 568 0.0 0.5- 940115 540 (4.6- 2.7+) 970701 422 0.2- 0.2+ 890801 568 0.3+ 0.4- 940115 540 (4.2- 1.9+) 970701 422 0.0 0.2- 890802 568 1.0+ 0.0 940115 540 (4.3- 1.9+) 970701 422 1.2- 0.4+ 890802 568 1.0+ 0.0 940115 540 (3.5- 0.9+) 970701 422 0.3- 0.0 891227 568 0.1- 0.6- 940115 540 (3.8- 1.0+) 970704 422 1.5- 0.2- 891227 568 0.6- 0.7- 940115 540 (4.4- 1.2+) 970704 422 0.9- 0.1- 891227 568 0.9- 0.5- 940118 107 (8.4- 5.2+) 970704 422 0.4+ 0.1+ 891227 568 0.8- 0.3- 940120 897 (2.8- 1.6+) 970704 422 1.3- 0.6+ 1990/ 940120 897 (3.1- 3.2+) 970705 422 0.6- 1.4- 900830 996 (0.7- 2.3+) 940120 897 (4.8- 2.6+) 970707 422 1.3+ 0.1- 900830 996 (0.3- 5.0+) 940124 897 (1.1- 2.4+) 970707 422 0.7+ 0.3+ 900920 657 1.6+ 0.2- 940124 897 (2.0- 3.3+) 970707 422 0.5+ 0.0 900920 372 1.4+ 1.8+ 940124 897 (2.6- 4.1+) 970707 422 1.0+ 1.0+ 900920 372 (3.1- 1.9+) 940125 897 (0.6- 3.1+) 970707 422 0.5+ 1.1+ 900926 503 (2.0+ 4.9+) 940125 897 (1.5+ 4.0+) 970707 422 0.9+ 0.1+ 900930 372 (1.1+ 2.8+) 940126 006 (6.8- 5.9+) 970707 422 0.4+ 0.9+ 900930 372 0.8- 1.5+ 940126 006 (5.3- 3.1+) 970710 422 1.1+ 0.8+ 901001 494 0.6- 1.6+ Y 940415 474 0.4- 0.3- 970710 422 1.1+ 0.3+ 1993/ 940415 474 1.2+ 0.3- 970710 422 0.7+ 0.1+ 930722 691 0.3- 0.6+ 940519 372 1.1+ 0.1- 970710 422 0.8+ 0.9+ 930722 691 1.9- 1.3+ 940605 360 0.7+ 0.5- 970710 422 1.9+ 1.2+ 930722 691 0.6- 0.6+ 940605 360 0.2+ 0.2- 970714 422 0.0 0.2+ 930725 691 0.5- 0.1+ 940614 691 0.7+ 0.7- 970714 422 0.3+ 0.4+ 930725 691 0.7- 0.2+ 940614 691 0.5- 0.2- 970714 422 0.1- 0.2+ 930725 691 0.5- 0.1+ 940703 360 0.6+ 0.5- 970714 422 0.0 0.5+ 930824 360 1.0+ 1.1- 940703 360 0.8+ 0.4- 970714 422 0.1+ 0.4+ 930824 360 1.6+ 0.3- 940710 691 0.1+ 0.0 970716 834 0.7- 0.5- 930825 360 0.2- 0.3- 940710 691 0.4+ 0.1+ 970716 834 0.5- 0.2- 930825 360 0.0 1.1- 940712 360 0.3+ 0.0 970716 834 1.2- 1.0+ 930825 360 0.5- 0.2- 940712 360 0.7+ 0.2+ 970717 834 1.6- 0.0 930914 385 0.9- 0.1+ 940803 360 0.0 0.8- 970717 834 0.4- 0.1- 930914 385 1.8+ 1.1- 940803 360 0.3+ 0.3- 970721 422 1.6- 0.4- 930914 376 1.8- 1.3- 940815 360 1.2+ 0.6- 970721 422 1.4- 0.6- 930914 376 0.4+ 1.7- 940815 360 1.2+ 0.6- 970721 422 1.5- 0.5- 930920 540 0.3+ 0.6- 941004 691 0.3- 0.1- 970721 422 1.1- 0.4- 930920 540 0.1- 0.4- 941004 691 1.3- 0.8- 970724 422 0.1- 0.2+ 930925 360 0.0 0.3- 941004 691 0.1+ 0.2+ 970724 422 0.0 0.3+ 930925 360 0.5+ 0.4- 1995/ 970724 422 0.4+ 0.3+ 930926 360 0.1- 0.5- 950819 327 0.1- 0.3- 970724 422 0.4+ 0.4+ 930926 360 0.1- 0.5- 950819 327 0.4- 0.4- 970724 422 0.1- 0.2+ 931009 360 0.2- 0.6- 950819 327 0.4+ 0.1- 970728 422 0.4- 1.1+ 931009 360 0.1+ 0.5- 950820 327 0.3+ 0.8+ 970728 422 0.8- 0.7+ 931011 360 0.1- 0.6- 950820 327 0.3- 0.0 970728 422 0.8- 0.9+ 931011 360 0.4- 0.7- 950820 327 0.4- 0.2- 970728 422 0.6- 0.6+ 931019 360 0.0 0.0 950823 327 0.5+ 0.0 970730 422 0.3- 0.0 931019 360 0.2+ 0.0 950823 327 0.5- 0.0 970730 422 0.1+ 0.1+ 931023 494 1.6+ 0.6+ 950823 327 0.2- 0.6- 970730 422 0.4+ 1.1+ 931023 494 0.3- 0.4- 950823 327 0.7+ 0.2- 970805 422 1.7+ 1.1- 931024 691 0.3- 0.3+ 950918 360 1.4+ 0.3+ 970805 422 1.5+ 0.2- 931024 691 0.2- 0.4+ 950918 360 1.9+ 0.1- 970805 422 1.7+ 1.0- 931024 691 0.8- 0.6+ 950918 360 1.2+ 0.9- 1998/ 931114 411 0.6+ 1.3- 1996/ 980916 693 0.9- 0.1- 931114 411 0.0 0.4+ 960724 360 0.2+ 0.6+ 980916 693 1.0- 0.2- 931114 494 (2.4- 0.1-) 960724 360 0.7+ 0.5+ 980916 693 0.7- 0.2- 931114 494 0.7- 0.3- 960817 568 0.3- 0.7+ 1999/ 931117 691 0.2+ 0.5+ 960818 360 0.8- 0.5+ 990909 704 1.1- 0.1- 931117 691 0.0 0.4+ 960818 360 0.9- 0.6+ 990909 704 0.8- 0.4+ 931117 691 0.0 0.4+ 960820 421 0.2+ 0.9+ 990909 704 0.8- 0.4- 931118 557 0.4- 0.7+ 960820 421 1.2- 0.4+ 990913 557 0.5- 0.3+ 931118 557 0.4- 0.6+ 960822 118 1.1- 0.7+ 990913 557 0.1- 0.2+ 931118 557 0.8- 0.6+ 960822 118 0.8- 0.4+ 990913 557 0.2+ 0.2+ 931118 557 0.6- 0.9+ 960823 118 0.1- 0.0 991009 360 0.3- 0.2- 931123 786 1.8+ 0.8+ 960824 118 0.3- 0.2+ 991009 360 0.3- 0.4- 931202 107 2.2+ 2.0- 960910 360 0.0 0.0 991009 360 0.4- 0.6- 931202 107 0.4+ 0.2+ 960910 360 0.3- 0.2+ 991113 695 0.9- 1.5+ 931204 107 0.8+ 1.3+ 960919 696 0.4+ 0.2+ 991113 695 0.6- 0.6+ 931204 107 0.7+ 0.0 960919 696 0.1+ 0.2+ 991113 695 1.2- 1.2+ 931206 107 0.4+ 0.1- 960919 696 0.2- 0.1+ 931207 360 0.0 0.0 961004 691 0.3+ 0.1+ ( ) -------- Rejected Obs.
Director, Computing Section Syuichi Nakano 2000 May 13