OAA computing section circular NK 517 Periodic Comet Wirtanen 1961 IV = 1967 XIV = 1974 XI
= 1985q The following improved orbital elements, by S. Nakano, are from 21 observations 1960 to 1986, including full planetary per- turbations and non-gravitational effect of style II. The comet approached Jupiter to within 0.27 AU in 1972 April and 0.47 AU in 1984 February, respectively. The mean residual is +/- 1.93 arc seconds: Epoch = 1986 Mar. 31.0 ET T = 1986 Mar. 19.13290 +/- 0.00082 (m.e.) ET Peri. = 356.04402 +/- 0.00084 Node = 81.65673 +/- 0.00086 (1950.0) Inc. = 11.67977 +/- 0.00018 q = 1.0846179 +/- 0.0000074 AU e = 0.6520174 +/- 0.0000035 a = 3.1168742 +/- 0.0000026 AU n_ = 0.17911220 +/- 0.00000022 P = 5.503 +/- 0.0000068 years A1 = +0.749 +/- 0.034 A2 = -0.12148 +/- 0.00524 T = 1961 Apr. 15.23291 ET Epoch = 1961 Apr. 11.0 ET Peri. = 343.50234 e = 0.5432850 Node = 86.46615 (1950.0) a = 3.5428814 AU Inc. = 13.38885 n_= 0.14779820 q = 1.6180872 AU P = 6.669 years T = 1967 Dec. 15.64638 ET Epoch = 1967 Dec. 16.0 ET Peri. = 343.60142 e = 0.5442245 Node = 86.40171 (1950.0) a = 3.5376444 AU Inc. = 13.40205 n_= 0.14812652 q = 1.6123716 AU P = 6.654 years T = 1974 July 5.64794 ET Epoch = 1974 July 12.0 ET Peri. = 351.82736 e = 0.6142547 Node = 83.54010 (1950.0) a = 3.2552598 AU Inc. = 12.26707 n_= 0.16781300 q = 1.2557012 AU P = 5.873 years ( T = 1980 May 22.57022 ET Epoch = 1980 June 10.0 ET Peri. = 351.93187 e = 0.6142248 Node = 83.49272 (1950.0) a = 3.2548876 AU Inc. = 12.26834 n_= 0.16784178 q = 1.2556549 AU P = 5.872 years ) The predicted orbit for the 1991 return is as follows: T = 1991 Sept.20.68670 ET Epoch = 1991 Sept.21.0 ET Peri. = 356.14665 e = 0.6522544 Node = 81.61342 (1950.0) a = 3.1151671 AU Inc. = 11.68256 n_= 0.17925945 q = 1.0832855 AU P = 5.498 years - continued - P/Wirtanen NK 517 - 2 The following residuals in seconds of arc are from the above orbital elements: Date/ UT R.A. (1950) Decl. *** O-C *** Code/Obs. h m s ! , " " " 1960 10 26.21933 22 20 21.95 -29 35 45.5 1.0+ 2.4+ 689/FS 1960 11 09.10803 22 25 03.51 -27 43 27.8 0.9- 0.2+ 689/FS 1960 11 12.11862 22 26 51.79 -27 14 32.2 0.1- 1.3- 689/FS 1960 12 18.11228 23 06 12.66 -19 46 07.2 1.6+ 0.7+ 689/FS 1961 01 08.11062 23 40 32.86 -14 11 24.0 2.5- 1.8- 689/FS 1961 01 10.11844 23 44 09.59 -13 36 57.5 0.2- 0.3+ 689/FS 1961 02 15.11940 00 56 52.95 -02 25 55.9 0.3+ 0.5- 689/FS 1967 10 05.73194 03 46 04.06 -02 32 22.3 0.8+ 2.9- 371/tm 1967 10 05.74271 03 46 04.37 -02 32 22.1 0.1- 2.6- 371/tm 1967 10 07.78299 03 47 17.65 -02 32 22.3 ( 0.9- 3.5-) 371/tm 1967 10 07.78715 03 47 17.76 -02 32 22.3 ( 1.2- 3.6-) 371/tm 1967 10 28.63194 03 51 46.00 -01 47 25.8 ( 4.0- 0.6+) 387/tm 1967 10 29.68958 03 51 35.63 -01 41 58.8 1.8+ 0.4+ 387/tm 1967 11 01.90903 03 50 50.32 -01 22 50.6 0.8+ 2.1+ 056/SP 1967 11 01.95069 03 50 49.27 -01 22 35.1 2.2- 1.2+ 056/SP 1967 11 24.90625 03 38 40.12 +03 03 04.8 0.4+ 1.9- 056/SP 1967 11 24.94792 03 38 38.58 +03 03 45.2 ( 3.3+ 2.9-) 056/SP 1968 03 24.14900 06 01 53.82 +32 38 17.3 1.3+ 1.2+ 693/CT 1974 12 20.51279 13 24.14 +03 38.6 5.5- 4.2+ 691/ST Y 1975 02 06.43900 14 00.89 +03 44.4 1.7+ 0.9- 691/ST Y 1975 02 06.50874 14 00.90 +03 44.7 1.8+ 0.6+ 691/ST Y 1985 11 13.43486 21 12 39.83 -29 11 52.1 0.4- 4.0+ 474/JN 1985 11 13.48463 21 12 43.49 -29 11 22.1 ( 1.6+ 5.7+) 474/JN 1985 12 09.43475 21 52 17.66 -24 18 38.8 0.0 3.2+ 474/JN 1985 12 09.46750 21 52 20.93 -24 18 10.0 ( 4.3- 5.3+) 474/JN 1985 12 10.43301 21 54 07.38 -24 05 11.5 ( 7.6- 1.7+) 474/JN 1986 03 31.87916 03 22 08.34 +19 58 31.7 2.6+ 0.9+ 984/LL 1986 04 01.86944 03 26 20.42 +20 23 08.3 2.6- 0.7- 984/LL ( ) -------- Rejected Obs.
Director, Computing Section Syuichi Nakano 1987 August 20