OAA computing section circular NK 658 2P/Encke
The following improved orbital elements, by S. Nakano, are from 202 observations 1982-1996, 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 +/- 0.88 arc second. See previous computations on NKs 485 (1985), 519 (1987), 545 (1990), 618 (1994). Epoch = 1997 June 1.0 TT T = 1997 May 23.59674 +/- 0.00019 (m.e.) TT Peri. = 186.27193 +/- 0.00009 Node = 334.72156 +/- 0.00009 (2000.0) Inc. = 11.92959 +/- 0.00003 q = 0.3313952 +/- 0.0000003 AU e = 0.8500136 +/- 0.0000002 a = 2.2095013 +/- 0.0000019 AU n' = 0.30009771 +/- 0.00000038 P = 3.284 +/- 0.0000042 years A1 = -0.007 +/- 0.004 A2 = -0.00164 +/- 0.00002 T = 1984 Mar. 27.68493 TT Epoch = 1984 Apr. 10.0 TT Peri. = 185.98725 e = 0.8463306 Node = 334.88908 (2000.0) a = 2.2190890 AU Inc. = 11.93280 n'= 0.29815492 q = 0.3410062 AU P = 3.306 years T = 1987 July 17.40108 TT Epoch = 1987 July 24.0 TT Peri. = 186.25292 e = 0.8498914 Node = 334.74055 (2000.0) a = 2.2099581 AU Inc. = 11.93140 n'= 0.30000467 q = 0.3317337 AU P = 3.285 years T = 1990 Oct. 28.56789 TT Epoch = 1990 Nov. 5.0 TT Peri. = 186.23471 e = 0.8502198 Node = 334.74925 (2000.0) a = 2.2091690 AU Inc. = 11.94502 n'= 0.30016542 q = 0.3308898 AU P = 3.284 years T = 1994 Feb. 9.47832 TT Epoch = 1994 Feb. 17.0 TT Peri. = 186.27097 e = 0.8502115 Node = 334.72867 (2000.0) a = 2.2092255 AU Inc. = 11.94035 n'= 0.30015392 q = 0.3309165 AU P = 3.284 years The predicted orbit for the 2000 return is as follows: T = 2000 Sept. 9.66165 TT Epoch = 2000 Sept.13.0 TT Peri. = 186.48282 e = 0.8468986 Node = 334.60073 (2000.0) a = 2.2177238 AU Inc. = 11.75568 n'= 0.29843027 q = 0.3395367 AU P = 3.303 years The following residuals in seconds of arc are from the above orbital elements: 820730 675 0.4+ 0.7- 901001 494 1.8+ 0.3- 940109 605 (5.9- 3.7+) 840127 372 (5.4- 3.0+) 930722 691 1.2- 0.7+ 940112 107 (7.2- 2.9+) 840225 168 (6.4- 1.9+) 930722 691 (2.8- 1.4+) 940113 107 (5.5- 2.5+) 840225 168 (7.8- 2.3+) 930722 691 1.5- 0.8+ 940115 540 (3.9- 2.3+) 840229 168 (3.6- 3.3+) 930725 691 1.4- 0.3+ 940115 540 (3.5- 1.6+) 840301 168 2.1- 0.8- 930725 691 1.5- 0.3+ 940115 540 (3.6- 1.5+) 840302 168 (3.1- 0.7+) 930725 691 1.3- 0.3+ 940115 540 (2.9- 0.6+) 840304 168 (2.4- 4.0+) 930824 360 1.2+ 1.1- 940115 540 (3.1- 0.6+) 840308 168 (4.8- 1.4+) 930824 360 1.8+ 0.2- 940115 540 (3.7- 0.9+) 840309 168 (5.5- 4.9-) 930825 360 0.0 0.2- 940118 107 (7.7- 4.9+) 840314 168 0.1- 0.5+ 930825 360 0.2+ 1.0- 940120 897 2.1- 1.2+ 840412 323 1.8- 0.2- 930825 360 0.3- 0.1- 940120 897 (2.4- 2.9+) 840413 323 0.7+ 0.3+ 930914 385 0.6- 0.2+ 940120 897 (4.0- 2.3+) 840423 474 (0.8- 4.9-) 930914 385 2.1+ 1.0- 940124 897 0.2- 2.1+ 840423 474 (0.3+ 6.0-) 930914 376 1.5- 1.3- 940124 897 (1.2- 3.0+) 840426 323 0.4+ 1.9- 930914 376 0.8+ 1.7- 940124 897 (1.8- 3.8+) 840427 323 0.4+ 2.0- 930920 540 0.7+ 0.5- 940125 897 (0.3+ 2.8+) 840502 323 2.1+ 0.3+ 930920 540 0.2+ 0.4- 940125 897 (2.3+ 3.8+) 840503 323 1.1- 2.3- 930925 360 0.4+ 0.2- 940126 006 (5.9- 5.6+) 840526 474 0.1+ 1.9+ 930925 360 0.9+ 0.3- 940126 006 (4.5- 2.9+) 840530 474 (4.8- 0.4-) 930926 360 0.3+ 0.4- 940415 474 0.9- 0.2+ 840530 474 1.3- 0.6+ 930926 360 0.2+ 0.5- 940415 474 0.7+ 0.3+ 840606 323 (0.5- 3.8-) 931009 360 0.3+ 0.6- 940519 372 0.5+ 0.6+ 840725 474 1.0+ 1.5- 931009 360 0.6+ 0.5- 940605 360 0.0 0.3+ 840725 474 0.4+ 1.4- 931011 360 0.4+ 0.6- 940605 360 0.5- 0.5+ 850726 691 1.0+ 0.8- 931011 360 0.0 0.7- 940614 691 1.0- 0.1+ 850726 691 0.1+ 1.1- 931019 360 0.5+ 0.0 940614 691 (2.3- 0.6+) 850726 691 0.3+ 1.6- 931019 360 0.7+ 0.0 940703 360 0.2- 0.4+ 850728 675 0.6+ 0.2- 931023 494 2.1+ 0.6+ 940703 360 0.0 0.5+ 850728 675 0.8+ 0.3- 931023 494 0.2+ 0.4- 940710 691 1.8- 0.9+ 850729 675 1.2+ 0.8- 931024 691 0.8- 0.3+ 940710 691 1.4- 1.0+ 850729 675 1.0+ 1.0- 931024 691 0.7- 0.4+ 940712 360 0.5- 1.0+ 850815 691 0.4+ 1.2- 931024 691 1.3- 0.5+ 940712 360 0.2- 1.2+ 850815 691 2.4+ 1.1- 931114 411 1.2+ 1.4- 940803 360 0.8- 0.1+ 850815 691 1.6+ 1.0- 931114 411 0.5+ 0.2+ 940803 360 0.5- 0.6+ 860831 691 0.6+ 1.7- 931114 494 1.9- 0.3- 940815 360 0.5+ 0.4+ 860831 691 0.3+ 0.7- 931114 494 0.2- 0.4- 940815 360 0.4+ 0.3+ 860831 691 0.0 0.7- 931117 691 0.3- 0.3+ 941004 691 1.8- 0.6+ 860901 691 1.0- 1.5- 931117 691 0.4- 0.3+ 941004 691 (2.7- 0.0 ) 860901 691 0.8- 0.6- 931117 691 0.5- 0.3+ 941004 691 1.3- 0.9+ 860902 691 0.2- 1.0- 931118 557 0.1+ 0.6+ 950819 327 0.5- 0.2+ 860902 691 0.3- 1.0- 931118 557 0.2+ 0.5+ 950819 327 0.9- 0.0 860902 691 0.3+ 1.2- 931118 557 0.2- 0.4+ 950819 327 0.0 0.3+ 860925 691 0.5+ 1.7- 931118 557 0.0 0.7+ 950820 327 0.1- 1.3+ 860925 691 0.5+ 1.2- 931123 786 (2.3+ 0.6+) 950820 327 0.7- 0.5+ 860926 691 0.2- 0.1- 931202 107 (2.8+ 2.2-) 950820 327 0.9- 0.2+ 860926 691 0.8- 0.5+ 931202 107 0.9+ 0.0 950823 327 0.1+ 0.4+ 860926 691 1.1- 0.2+ 931204 107 1.3+ 1.1+ 950823 327 0.9- 0.5+ 870813 474 (3.9- 0.5+) 931204 107 1.2+ 0.2- 950823 327 0.6- 0.2- 870813 474 1.4- 0.8- 931206 107 1.0+ 0.4- 950823 327 0.3+ 0.2+ 870815 323 1.0+ 1.1+ 931207 360 0.6+ 0.3- 950918 360 1.0+ 0.8+ 870817 323 2.2- 0.5+ 931207 360 0.7+ 0.3- 950918 360 1.6+ 0.4+ 870818 323 (4.2- 1.3-) 931208 691 0.6- 0.1- 950918 360 0.9+ 0.5- 870819 474 (4.7+ 1.9-) 931208 691 0.4- 0.2- 960724 360 0.3- 0.6+ 870819 474 1.3- 1.2+ 931208 691 0.7- 0.0 960724 360 0.2+ 0.5+ 880517 568 (3.4+ 0.0 ) 931208 360 0.4- 0.3- 960817 568 0.9- 0.6+ 880518 568 1.5+ 1.1+ 931208 360 0.3- 0.1- 960818 360 1.4- 0.4+ 880909 568 1.9+ 0.4+ 931211 107 2.0- 0.1+ 960818 360 1.4- 0.5+ 880909 568 2.6+ 1.0+ 931211 107 0.0 1.3+ 960820 421 0.3- 0.8+ 880909 568 2.0+ 0.7+ 931212 107 0.1- 1.9+ 960820 421 1.7- 0.3+ 880909 568 (2.9+ 1.4+) 931214 897 (4.6- 1.2+) 960822 118 1.7- 0.6+ 880909 568 (3.4+ 1.2+) 931214 897 (5.0- 2.4+) 960822 118 1.3- 0.3+ 880909 568 (4.7+ 1.9+) 931216 107 0.9+ 0.1- 960823 118 0.6- 0.2- 880911 568 0.5- 1.2+ 931216 107 1.5+ 0.1- 960824 118 0.8- 0.1+ 880911 568 0.2+ 0.7+ 931217 897 (5.8- 0.4-) 960910 360 0.5- 0.1- 880912 568 0.3- 1.9+ 931217 897 (7.2- 0.4+) 960910 360 0.8- 0.0 880912 568 0.6- 2.1+ 931217 897 (7.5- 2.0+) 960919 696 0.0 0.0 880912 568 (1.4- 3.1+) 931217 107 1.1+ 1.1+ 960919 696 0.3- 0.1+ 890601 568 1.7+ 0.6- 931217 107 0.7- 0.2- 960919 696 0.7- 0.0 890601 568 0.8+ 0.9- 931223 107 1.1- 1.0- 961004 691 1.1- 0.1- 890602 568 0.3- 1.2+ 931224 897 (6.9- 3.6+)Y 961004 691 0.9- 0.2- 890602 568 0.1- 0.0 931224 897(10.6- 1.8+)Y 961005 360 0.0 0.5+ 890602 568 0.2- 0.6+ 931227 897 (3.2- 1.7+) 961005 360 0.2+ 0.3+ 890801 568 0.0 0.0 931227 897 (5.3- 1.1+) 961012 691 (2.5+ 0.5-) 890801 568 0.1- 0.1- 931227 107 (3.1- 1.4+) 961012 691 1.1- 0.2- 890801 568 0.2+ 0.1+ 931227 107 (3.2- 2.8+) 961012 691 1.1- 0.4+ 890802 568 0.9+ 0.4+ 931228 107 (3.8- 1.6-) 961012 118 0.1+ 0.4+ 890802 568 0.9+ 0.4+ 931228 107 (5.9- 1.6+) 961012 118 0.4+ 0.2+ 891227 568 0.1- 0.4- 940102 410 (4.0- 1.6+) 961016 360 0.6- 0.1- 891227 568 0.6- 0.5- 940102 410 1.3+ 0.4- 961016 360 0.9- 0.7- 891227 568 0.9- 0.3- 940104 887 0.1+ 0.3- 961103 118 1.3+ 0.6+ 891227 568 0.8- 0.1- 940104 887 0.0 0.5- 961103 118 1.0+ 0.7+ 900830 996 1.2+ 1.8+ 940105 691 0.1- 0.1- 961104 118 1.4+ 0.5+ 900830 996 (1.6+ 4.5+) 940105 691 0.6- 0.1- 961104 118 1.5+ 0.5+ 900920 657 (3.8+ 2.0-) 940107 897 (3.0- 1.9+) 961228 360 0.7+ 0.8+ 900920 372 (3.6+ 0.0 ) 940107 897 (2.4- 2.1+) 961228 360 0.2+ 0.5+ 900920 372 0.9- 0.1+ 940109 360 0.1- 0.8+ 961230 867 0.5+ 0.3- 900926 503 (4.0+ 2.8+) 940109 360 0.7- 0.8+ 961230 867 0.8+ 0.3- 900930 372 (2.9+ 0.5+) 940109 605 (6.7- 2.6+) 961230 867 0.9+ 1.1+ 900930 372 1.0+ 0.8- 940109 605 (7.7- 0.9+) ( ) -------- Rejected Obs.
Director, Computing Section Syuichi Nakano 1997 May 4