OAA computing section circular NK 485 Periodic Comet Encke 1971 II = 1974 V = 1977 XI = 1980 XI
= 1984 VI The following improved orbital elements, by S. Nakano, are from 93 observations 1970 to 1985, including full planetary per- turbations and non-gravitational effect of style II. The mean residual is +/- 1.85 arc seconds. Epoch = 1984 Apr. 10.0 ET T = 1984 Mar. 27.68455 +/- 0.00012 (m.e.) ET Peri. = 185.99665 +/- 0.00035 Node = 334.18152 +/- 0.00035 (1950.0) Inc. = 11.92687 +/- 0.00007 q = 0.3410063 +/- 0.0000007 AU e = 0.8463313 +/- 0.0000003 a = 2.2191002 +/- 0.0000002 AU nß = 0.29815268 +/- 0.0000000008 P = 3.306 +/- 0.0000005 years A1 = -0.033 +/- 0.008 A2 = -0.00303 +/- 0.00002 T = 1971 Jan. 9.98250 ET Epoch = 1971 Jan. 9.0 ET Peri. = 185.94736 e = 0.8471581 Node = 334.21334 (1950.0) a = 2.2173447 AU Inc. = 11.97316 nß= 0.29850682 q = 0.3389032 AU P = 3.302 years T = 1974 Apr. 28.99906 ET Epoch = 1974 Apr. 23.0 ET Peri. = 185.93197 e = 0.8474521 Node = 334.21945 (1950.0) a = 2.2165405 AU Inc. = 11.98147 nß= 0.29866928 q = 0.3381285 AU P = 3.300 years T = 1977 Aug. 17.00896 ET Epoch = 1977 Aug. 5.0 ET Peri. = 185.95634 e = 0.8464722 Node = 334.20658 (1950.0) a = 2.2189201 AU Inc. = 11.93831 nß= 0.29818898 q = 0.3406659 AU P = 3.305 years T = 1980 Dec. 6.57825 ET Epoch = 1980 Nov. 17.0 ET Peri. = 185.98274 e = 0.8467577 Node = 334.19480 (1950.0) a = 2.2183485 AU Inc. = 11.94548 nß= 0.29830422 q = 0.3399448 AU P = 3.304 years The predicted orbit for the 1987 return is as follows: T = 1987 July 17.39768 ET Epoch = 1987 July 24.0 ET Peri. = 186.26246 e = 0.8498922 Node = 334.03292 (1950.0) a = 2.2099707 AU Inc. = 11.92549 nß= 0.30000211 q = 0.3317338 AU P = 3.285 years - continued - NK 485 - 2 The following residuals in seconds of arc (or two decimals in degrees) are from the above orbital elements: Date/ UT R.A. (1950) Decl. *** O-C *** Code/Obs. h m s ¡ , " " " 1970 09 26.42054 01 44.6 +28 26 (33.4+ 5.4+) 691/ST X 1970 10 21.84832 00 28 15.30 +30 14 12.6 3.9- 2.9- 993/WL 1970 11 01.73581 23 32 17.21 +28 02 36.6 1.9+ 3.5- 095/cl 1970 11 01.74274 23 32 14.85 +28 02 28.3 1.7+ 3.5- 095/cl 1970 11 16.75845 22 08 33.02 +20 28 38.9 0.5+ 0.3- 020/NI 1970 11 16.76607 22 08 30.39 +20 28 19.6 1.5- 2.0- 020/NI 1970 11 17.82249 22 02 53.17 +19 47 12.7 ( 8.1- 0.9-) 046/mr 1970 11 19.78030 21 52 39.96 +18 29 01.5 4.1- 0.5- 095/CR 1970 11 19.78784 21 52 37.63 +18 28 41.9 3.5- 1.6- 095/CR 1970 11 21.74091 21 42 38.56 +17 08 25.3 ( 6.3- 1.0-) 119/bj 1970 11 21.75383 21 42 35.50 +17 07 29.9 ( 1.2- 24.7-) 020/ml 1970 11 21.76145 21 42 32.85 +17 07 35.3 ( 5.4- 0.2-) 020/NI 1970 11 23.41944 21 34 14.50 +15 57 55.0 0.2+ 2.2- 370/sk 1970 11 23.72878 21 32 42.24 +15 44 38.4 ( 5.3- 5.8-) 046/mr 1970 11 25.75811 21 22 44.59 +14 17 32.1 ( 5.2- 3.9-) 046/KL 1970 11 25.85069 21 22 16.91 +14 13 34.6 ( 9.3- 1.2+) 056/an 1970 11 25.86250 21 22 13.67 +14 13 02.2 ( 6.1- 0.3-) 056/an 1970 11 26.69125 21 18 13.83 +13 37 04.7 1.1+ 2.1+ 095/CR 1970 11 26.70728 21 18 08.66 +13 36 19.0 ( 5.3- 1.4-) 095/CR 1970 11 26.75694 21 17 54.32 +13 34 07.9 ( 4.6- 1.0-) 056/SP 1970 11 26.80992 21 17 37.91 +13 31 44.4 (18.1- 5.3-) 046/mr 1970 11 27.76694 21 13 03.18 +12 49 48.8 2.8- 3.4- 046/KL 1970 11 28.69653 21 08 36.36 +12 08 59.5 (12.5- 10.5+) 056/an 1970 11 28.71806 21 08 29.78 +12 07 51.2 (17.1- 0.4-) 056/an 1970 11 28.72847 21 08 26.61 +12 07 27.6 (19.2- 3.8+) 056/an 1970 11 28.75035 21 08 27.46 +12 07 17.7 (85.4+ 52.1+) 046/mr 1970 11 30.51806 20 59 57.86 +10 47 57.9 2.3- 1.1+ 323/PR 1970 11 30.73041 20 58 57.87 +10 38 00.3 0.1+ 1.1+ 119/AB 1970 11 30.73898 20 58 54.3 +10 37 48 (23.3- 12.5+) 011/lo Y 1970 12 04.69288 20 40 15.46 +07 36 32.6 ( 4.1- 5.4-) 046/mr 1970 12 05.38646 20 36 58.01 +07 04 20.7 0.1+ 3.9+ 370/sk 1970 12 05.39063 20 36 56.93 +07 04 08.6 2.0+ 3.5+ 370/sk 1970 12 06.70553 20 30 40.56 +06 01 51.8 1.4- 1.2- 046/KL 1970 12 06.72887 20 30 33.2 +06 00 46 (10.3- 0.7-) 011/lo Y 1970 12 19.69269 19 23 22.45 -05 15 51.7 ( 4.4+ 8.8+) 046/mr 1970 12 21.66392 19 12 07.52 -07 10 06.4 (11.5+ 4.7+) 095/cl 1971 05 27.43056 22 39 32.24 -14 52 26.9 2.0+ 1.0+ 693/CT 1971 05 29.42465 22 39 46.17 -14 52 16.8 2.6+ 1.4+ 691/ST 1972 08 15.28299 23 00.91 -04 50.2 2.3- 2.5- 691/ST Y 1972 08 15.35764 23 00.85 -04 50.5 3.5+ 0.5- 691/ST Y 1972 09 05.20593 22 41 09.62 -06 32 29.3 ( 8.6+ 3.4+) 801/HO 1972 09 13.22083 22 33 27.79 -07 12 37.1 0.6+ 0.1- 691/ST 1972 09 13.29236 22 33 23.77 -07 12 57.6 1.8+ 0.4+ 691/ST 1973 09 21.22523 00 01 43.51 +09 35 05.8 2.4+ 0.6+ 691/ST 1973 09 21.22523 00 01 43.51 +09 35 05.8 2.4+ 0.6+ 691/ST 1973 09 21.25110 00 01 41.20 +09 34 55.4 1.7+ 0.2+ 691/ST 1973 09 21.25110 00 01 41.20 +09 34 55.4 1.7+ 0.2+ 691/ST 1973 10 22.22205 23 17 02.58 +05 24 20.4 1.9+ 0.5+ 691/ST 1973 10 22.26551 23 16 59.28 +05 23 58.6 2.3+ 0.8+ 691/ST 1973 10 24.19965 23 14 37.32 +05 07 41.7 ( 2.4+ 4.6-) 801/HO - continued - NK 485 - 3 Date/ UT R.A. (1950) Decl. *** O-C *** Code/Obs. h m s ¡ , " " " 1973 10 24.99653 23 14 37.32 +05 07 41.7 ( 0.24+ 0.11+) 801/sa 1974 05 30.71926 02 02 27.71 -13 04 42.8 (11.2+ 14.7+) 474/JN 1974 07 20.43310 20 08 14.87 -40 53 00.2 1.3- 0.2+ 485/CA 1974 07 20.43333 20 08 14.89 -40 53 01.2 0.3- 1.0- 485/CA 1974 09 12.13194 19 01 36.32 -30 09 48.7 1.0+ 0.5- 691/ST 1974 09 12.17608 19 01 37.34 -30 09 28.6 1.3+ 0.0 691/ST 1975 09 01.17745 22 22 48.54 -09 55 51.4 0.6- 1.3+ 801/HO 1975 09 12.21972 22 12 00.82 -10 47 47.0 1.0+ 0.8+ 691/ST 1975 09 12.26419 22 11 58.28 -10 47 58.3 1.0+ 1.3+ 691/ST 1976 09 20.21875 23 23 40.88 +02 15 17.8 1.6+ 0.4+ 691/ST 1976 09 20.26042 23 23 38.00 +02 15 01.9 2.1+ 0.2+ 691/ST 1977 07 14.44444 05 37 10 +29 27.2 (35.5+ 7.0+) 688/LO Y 1977 07 14.76458 05 39 12 +29 27.2 (72.9+ 6.1+) 372/sk Y 1977 07 14.78681 05 39 16.20 +29 27 06.0 (19.3+ 0.0 ) 372/sk 1977 07 20.45972 06 16 28.62 +29 05 54.7 ( 8.7+ 1.2-) 688/LO 1977 08 30.45556 11 46 33.81 -03 28 52.7 0.9- 3.0- 323/PR 1977 08 30.46597 11 46 38.46 -03 29 32.2 1.2- 2.2- 323/PR 1977 08 31.45556 11 54 00.85 -04 32 55.7 3.8- 0.0 323/PR 1977 08 31.46330 11 54 04.29 -04 33 26.8 3.9- 1.6- 323/PR 1977 09 01.45694 12 01 25.75 -05 35 59.1 3.4- 0.8+ 323/PR 1977 09 02.45972 12 08 48.49 -06 37 58.9 3.1- 0.0 323/PR 1977 09 05.45694 12 30 36.54 -09 35 43.4 2.7- 0.3- 323/PR 1977 09 07.45972 12 44 58.49 -11 27 44.7 3.2- 2.2- 323/PR 1977 09 09.46319 12 59 11.26 -13 13 54.4 0.2- 0.4- 323/PR 1977 09 11.30215 13 12 04.94 -14 46 00.3 0.9+ 1.8- 485/CA 1977 09 11.31327 13 12 09.56 -14 46 32.1 0.5+ 1.2- 485/CA 1977 09 11.45833 13 13 09.94 -14 53 31.5 2.6- 2.7+ 323/PR 1977 09 12.00096 13 16 56.26 -15 19 37.8 1.6- 1.9- 809/ES 1977 09 13.46736 13 27 03.68 -16 27 36.9 0.4+ 1.8- 323/PR 1977 09 18.47986 14 00 47.33 -19 53 45.2 1.3+ 1.0- 323/PR 1977 10 04.51250 15 36 54.62 -26 41 19.8 2.3- 0.8- 323/PR 1977 10 09.33521 16 01 50.64 -27 43 56.7 2.5+ 0.3+ 485/CA 1977 10 09.35973 16 01 58.07 -27 44 12.0 4.1+ 0.6+ 485/CA 1977 10 10.02562 16 05 15.30 -27 51 14.9 2.0- 1.7- 809/ES 1977 10 14.35050 16 25 49.58 -28 28 14.6 ( 7.1- 1.3-) 485/CA 1978 07 31.19454 22 29 39.49 -11 32 49.1 (82.7- 20.8+) 801/HO 1978 09 02.21497 21 53 31.48 -14 20 01.1 2.0+ 1.8+ 801/HO 1979 08 31.26525 23 17 25.86 -00 48 42.7 0.7+ 1.0- 801/HO 1979 09 17.19872 23 00 29.32 -02 19 22.1 1.8- 0.3- 801/HO 1979 09 24.25418 22 53 31.50 -02 58 11.3 1.9+ 2.4+ 801/HO 1980 08 08.46458 02 39 47.6 +25 08 49 ( 7.5- 6.2+) 675/PL 1980 08 13.28166 02 46 24.70 +26 11 09.8 0.2+ 0.7+ 801/HO 1980 09 09.32078 03 28 09.52 +33 37 12.4 1.6+ 1.1+ 801/HO 1980 09 12.79306 03 34 42.2 +34 54 49 ( 6.7+ 20.8+) 372/sk 1980 10 04.76719 04 41 47 +47 21.8 (13.3+ 17.9+) 372/sk Y 1980 10 04.97640 04 42 54.88 +47 31 52.8 ( 8.8+ 5.8+) 993/WL 1980 10 08.36310 05 04 09.27 +50 32 37.2 4.1+ 0.1- 801/HO 1980 10 08.71632 05 06 48 +50 53.0 (15.8+ 15.7+) 372/sk Y 1980 10 13.00213 05 47 14.86 +55 10 42.2 (14.2+ 14.3+) 022/PN 1980 10 13.01737 05 47 26.70 +55 11 34.2 (24.1+ 8.8+) 022/PN - continued - NK 485 - 4 Date/ UT R.A. (1950) Decl. *** O-C *** Code/Obs. h m s ¡ , " " " 1980 10 20.02492 07 53 39.87 +60 52 49.8 (23.3+ 1.0+) 022/PN 1980 10 20.04535 07 54 11.46 +60 53 12.5 (29.4+ 1.7+) 022/PN 1980 10 20.10086 07 55 35.66 +60 54 19.7 (37.3+ 12.7+) 547/BR 1980 10 20.11955 07 56 03.21 +60 54 26.5 (32.8+ 1.6+) 547/BR 1980 10 21.78333 08 40 27 +60 53.1 (24.9+ 10.1-) 372/sk Y 1980 11 03.42918 12 56 11.88 +32 01 43.1 ( 7.1+ 10.7-) 801/HO 1980 11 04.48368 13 06 01.90 +28 53 43.2 ( 2.6+ 11.7-) 688/LO 1980 11 04.50313 13 06 12.40 +28 50 15.7 ( 5.8+ 16.2-) 688/LO 1980 11 04.50938 13 06 15.42 +28 49 16.6 ( 2.3+ 10.2-) 688/LO 1980 11 18.84491 14 19 12.28 -00 49 47.9 0.4+ 2.4- 882/sz 1980 11 18.84618 14 19 12.55 -00 49 55.1 0.7+ 3.3- 882/sz 1980 11 20.22219 14 23 39.29 -02 40 38.7 ( 1.2- 4.7-) 006/FB 1980 11 20.22929 14 23 40.60 -02 41 09.5 1.8- 2.2- 006/FB 1982 07 30.43132 23 19 49.62 -02 41 23.3 0.7- 0.6+ 675/PL 1984 01 27.42569 23 32 56.15 +05 38 22.0 ( 5.9- 3.1+) 372/sk 1984 02 25.63374 00 25 58.80 +10 14 08.3 ( 6.8- 1.8+) 168/KO 1984 02 25.63790 00 25 59.26 +10 14 11.4 ( 8.2- 2.3+) 168/KO 1984 02 29.63200 00 35 06.49 +10 56 03.0 3.9- 3.2+ 168/KO 1984 03 01.63721 00 37 28.24 +11 06 12.6 2.4- 0.9- 168/KO 1984 03 02.63513 00 39 50.22 +11 16 11.6 3.4- 0.6+ 168/KO 1984 03 04.62957 00 44 37.87 +11 35 21.6 2.8- 4.0+ 168/KO 1984 03 08.64010 00 54 24.92 +12 08 38.8 ( 5.1- 1.3+) 168/KO 1984 03 09.63715 00 56 50.77 +12 15 14.5 ( 5.7- 5.0-) 168/KO 1984 03 14.65145 01 08 32.89 +12 32 10.7 0.0 0.5+ 168/KO 1984 04 12.88576 23 56 14.69 -10 53 26.3 0.0 1.7+ 323/PR 1984 04 13.89792 23 52 58.93 -11 30 47.0 2.2+ 2.1+ 323/PR 1984 04 23.74815 23 32 39.01 -15 12 17.5 0.4- 3.5- 474/JN 1984 04 23.75544 23 32 38.51 -15 12 24.7 ( 0.7+ 4.6-) 474/JN 1984 04 26.89028 23 29 05.22 -15 50 05.5 0.5+ 0.5- 323/PR 1984 04 27.89201 23 28 07.59 -16 00 20.3 0.4+ 0.7- 323/PR 1984 05 02.87812 23 24 13.72 -16 42 31.1 1.8+ 1.7+ 323/PR 1984 05 03.88194 23 23 34.07 -16 49 48.2 1.3- 0.9- 323/PR 1984 05 26.76214 23 09 06.27 -19 20 54.7 0.9- 3.4+ 474/JN 1984 05 30.68242 23 05 25.38 -19 53 40.0 ( 6.0- 1.2+) 474/JN 1984 05 30.70834 23 05 23.97 -19 53 53.0 2.6- 2.2+ 474/JN 1984 06 06.88524 22 56 53.39 -21 03 04.5 2.0- 2.2- 323/PR 1984 07 25.51852 20 55 51.57 -29 29 30.4 0.9- 0.6+ 474/JN 1984 07 25.56192 20 55 44.04 -29 29 39.9 1.6- 0.8+ 474/JN 1985 07 26.38851 23 01 44.43 -06 06 37.6 0.7- 0.3+ 691/ST 1985 07 26.39976 23 01 43.90 -06 06 40.2 1.7- 0.1- 691/ST 1985 07 26.41860 23 01 43.13 -06 06 44.5 1.5- 0.6- 691/ST 1985 07 28.43222 23 00 19.42 -06 13 40.2 1.1- 0.9+ 675/PL 1985 07 28.43597 23 00 19.27 -06 13 41.1 0.9- 0.8+ 675/PL 1985 07 29.46146 22 59 35.14 -06 17 22.5 0.5- 0.3+ 675/PL 1985 07 29.46545 22 59 34.95 -06 17 23.5 0.7- 0.1+ 675/PL 1985 08 15.25980 22 45 28.86 -07 29 01.3 1.3- 0.1- 691/ST 1985 08 15.27624 22 45 28.05 -07 29 06.0 0.6+ 0.0 691/ST 1985 08 15.29233 22 45 27.08 -07 29 10.4 0.1- 0.2+ 691/ST ( ) -------- Rejected Obs.
Director, Computing Section Syuichi Nakano 1985 December 22