OAA computing section circular NK 480 Periodic Comet Grigg-Skjellerup 1967 I = 1972 II = 1977 VI

= 1982 IV The following improved orbital elements, by S. Nakano, are from 68 observations 1967 to 1982, including full planetary per- turbations and non-gravitational effect of style II. The mean residual is +/- 1.26 arc seconds. Epoch = 1982 May 31.0 ET T = 1982 May 14.99637 +/- 0.00011 (m.e.) ET Peri. = 359.32755 +/- 0.00016 Node = 212.63247 +/- 0.00009 (1950.0) Inc. = 21.13653 +/- 0.00004 q = 0.9892469 +/- 0.0000005 AU e = 0.6656801 +/- 0.0000001 a = 2.9589833 +/- 0.0000013 AU nß = 0.19363787 +/- 0.000000002 P = 5.090 +/- 0.0000034 years A1 = +0.008 +/- A2 = -0.00105 +/- T = 1967 Jan. 16.47480 ET Epoch = 1967 Jan. 30.0 ET Peri. = 359.17039 e = 0.6624353 Node = 212.68546 (1950.0) a = 2.9711435 AU Inc. = 21.04929 nß= 0.19245031 q = 1.0029532 AU P = 5.121 years T = 1972 Mar. 2.65241 ET Epoch = 1972 Feb. 13.0 ET Peri. = 359.28166 e = 0.6628375 Node = 212.65179 (1950.0) a = 2.9698066 AU Inc. = 21.06723 nß= 0.19258028 q = 1.0013075 AU P = 5.118 years T = 1977 Apr. 11.00030 ET Epoch = 1977 Apr. 7.0 ET Peri. = 359.32154 e = 0.6647055 Node = 212.64488 (1950.0) a = 2.9627246 AU Inc. = 21.10366 nß= 0.19327120 q = 0.9933853 AU P = 5.100 years The predicted orbit for the 1987 return is as follows: T = 1987 June 18.04595 ET Epoch = 1987 June 14.0 ET Peri. = 359.31638 e = 0.6647127 Node = 212.62671 (1950.0) a = 2.9625415 AU Inc. = 21.10576 nß= 0.19328912 q = 0.9933025 AU P = 5.099 years There are the residuals, in seconds of arc, from the above orbital elements on the next pages: - continued - NK 480 - 2 Date/ UT R.A. (1950) Decl. *** O-C *** Code/Obs. h m s ¡ , " " " 1966 12 19.52847 14 25 23.66 -23 19 17.9 1.9+ 2.8- 675/PL 1966 12 19.54375 14 25 28.09 -23 19 21.0 0.2+ 0.8+ 675/PL 1972 01 13.31944 13 35 32.00 -34 13 51.2 1.0- 0.0 808/YS 1972 01 26.32159 14 53 13.88 -36 11 17.4 ( 8.4- 3.4-) 805/EL 1972 01 26.33027 14 53 17.21 -36 11 20.4 ( 7.8- 5.5-) 805/EL 1972 01 26.33964 14 53 20.43 -36 11 21.4 (11.6- 5.5-) 805/EL 1972 02 12.52460 16 42 59.49 -33 12 26.2 1.2- 0.5- 691/ST 1972 02 12.53553 16 43 03.50 -33 12 11.8 0.9- 0.2- 691/ST 1972 05 13.40833 21 42 59.48 +12 40 57.5 0.7- 0.8+ 693/CT 1972 05 13.44792 21 43 02.38 +12 41 46.1 0.2- 0.5- 693/CT 1972 05 18.45058 21 48 45.85 +14 23 02.5 0.6+ 0.1+ 691/ST 1972 07 13.36626 21 47 34.75 +24 41 06.8 0.1+ 0.1+ 691/ST 1972 07 13.40972 21 47 31.88 +24 41 06.9 0.6- 0.3+ 691/ST 1972 08 14.26806 21 09 27.52 +20 35 39.3 0.4- 0.4- 691/ST 1972 08 14.33160 21 09 23.14 +20 34 45.0 0.5- 0.7- 691/ST 1977 01 21.73495 09 44 43.84 -37 55 23.1 ( 1.7+ 4.7+) 323/PR 1977 01 25.61562 09 47 12.46 -40 14 18.5 0.0 2.0+ 323/PR 1977 01 26.53805 09 47 47.15 -40 47 55.8 2.6- 2.1- 485/CA 1977 01 26.58183 09 47 48.87 -40 49 30.3 0.6+ 0.5- 485/CA 1977 01 27.74375 09 48 33.75 -41 32 06.9 0.0 0.1+ 323/PR 1977 03 09.71466 11 45 28.75 -72 52 06.8 1.6+ 1.1+ 323/PR 1977 03 11.42867 12 12 09.27 -74 23 59.4 1.7+ 0.2- 485/CA 1977 03 11.44969 12 12 30.83 -74 25 06.8 1.1+ 0.9- 485/CA 1977 03 14.74267 13 27 24.52 -76 43 20.0 ( 0.4+ 3.1+) 323/PR 1977 03 16.72083 14 28 54.07 -77 15 12.8 ( 3.2+ 0.3-) 323/PR 1977 03 17.68246 15 01 34.94 -77 09 02.2 1.8- 1.1+ 323/PR 1977 03 18.63021 15 34 00.83 -76 46 48.2 2.6- 0.9+ 323/PR 1977 03 19.47837 16 02 08.61 -76 13 00.5 2.5+ 2.2- 485/CA 1977 03 19.49354 16 02 37.09 -76 12 18.2 0.1- 0.8- 485/CA 1977 03 21.64705 17 05 34.27 -73 48 03.3 0.4+ 2.1+ 323/PR 1977 03 25.79736 18 26 11.98 -66 01 48.6 ( 0.4+ 5.8-) 323/PR 1977 03 25.85250 18 26 56.57 -65 54 20.8 0.3- 0.5- 323/PR 1977 03 30.78872 19 16 43.86 -53 09 32.6 ( 5.2+ 4.0+) 323/PR 1977 04 01.35556 19 27 00.51 -48 41 01.6 0.2+ 1.2+ 807/CE 1977 04 01.39722 19 27 14.80 -48 33 49.3 ( 2.0+ 4.4+) 807/CE 1977 04 01.40764 19 27 18.37 -48 32 07.8 2.7+ 1.8- 807/CE 1977 04 16.35716 20 16 54.16 -09 27 45.9 1.0+ 0.6+ 801/HO 1977 04 16.78507 20 17 41.82 -08 36 30.5 2.8- 2.5- 882/sz 1977 04 16.78854 20 17 42.22 -08 36 01.2 2.0- 2.2+ 882/sz 1977 04 18.77431 20 21 10.8 -04 51 19 ( 0.2- 8.1-) 372/sk Y 1977 04 20.77431 20 24 20.3 -01 25 05 ( 4.2+ 5.6+) 372/sk Y 1977 04 20.77986 20 24 20.79 -01 24 39.6 ( 6.6+ 0.8-) 882/sz 1977 04 20.78507 20 24 20.93 -01 24 07.0 2.4+ 1.2+ 882/sz 1977 04 21.7889 20 25 48.9 +00 12 01 1.4+ 1.5+ 879/fr Y 1977 04 22.32032 20 26 34.31 +01 01 42.8 2.1+ 2.8+ 805/EL 1977 04 22.72564 20 27 06.88 +01 38 15.7 1.8+ 2.3- 485/CA 1977 04 22.72917 20 27 07.09 +01 38 34.1 1.2+ 2.8- 485/CA 1977 04 22.74200 20 27 07.94 +01 39 45.9 0.2+ 0.2+ 485/CA 1977 04 22.81708 20 27 15.02 +01 46 22.6 0.1+ 0.1+ 323/PR 1977 04 28.77535 20 34 18.06 +09 27 44.7 2.2+ 1.1+ 882/sz - continued - NK 480 - 3 Date/ UT R.A. (1950) Decl. *** O-C *** Code/Obs. h m s ¡ , " " " 1977 04 28.78750 20 34 18.52 +09 28 29.5 ( 0.5- 3.3-) 882/sz 1977 05 13.99551 20 44 41.23 +22 03 20.8 0.8- 1.8+ 993/WL 1977 05 17.34044 20 45 35.47 +23 57 22.6 0.6- 0.8- 801/HO 1977 05 20.02352 20 45 58.24 +25 18 59.6 ( 4.5+ 1.1-) 993/WL 1977 05 20.68125 20 46 00.13 +25 37 57.2 ( 3.4- 1.5+) 879/fr 1977 06 16.24991 20 31 49.24 +32 54 25.3 0.2- 0.7- 801/HO 1977 08 10.17636 19 33 41.44 +21 48 24.5 3.1- 0.2+ 801/HO 1982 01 15.28683 07 12 47.75 -20 35 52.8 2.1+ 0.2+ 675/PL 1982 01 16.31669 07 11 13.06 -20 46 14.3 1.0+ 0.8+ 675/PL 1982 03 23.07213 06 21 08.69 -12 32 16.8 0.5+ 0.3- 801/HO 1982 03 26.01641 06 24 00.13 -11 31 28.5 1.2+ 0.7+ 801/HO 1982 04 01.15702 06 31 36.83 -09 16 25.9 0.6+ 0.1- 675/PL 1982 04 11.15243 06 48 53.24 -05 08 03.1 0.3+ 0.4+ 707/ev 1982 04 13.05104 06 52 52.85 -04 15 51.7 0.6+ 0.7+ 801/HO 1982 04 19.04161 07 07 05.54 -01 17 50.4 0.1+ 0.2- 801/HO 1982 04 29.07513 07 37 08.99 +04 37 33.5 0.3- 0.3- 801/HO 1982 04 29.07513 07 37 08.99 +04 37 33.5 0.3- 0.3- 801/HO 1982 05 19.08647 09 10 35.67 +21 06 09.5 0.3+ 0.5+ 801/HO 1982 06 13.21493 12 36 02.59 +38 36 15.3 0.5+ 0.6- 707/ev 1982 06 14.58090 12 48 03.42 +38 48 04.6 0.0 0.1+ 372/sk 1982 06 18.95102 13 24 46.61 +38 52 05.2 0.4- 0.7- 491/CN 1982 06 19.05422 13 25 35.76 +38 51 32.3 2.4- 0.9+ 491/CN 1982 06 19.15278 13 26 23.83 +38 51 07.4 0.7+ 0.6- 801/HO 1982 06 19.15906 13 26 26.83 +38 51 03.9 0.9+ 1.9- 801/HO 1982 06 21.08120 13 41 30.60 +38 37 41.8 1.8+ 1.0+ 801/HO 1982 06 23.11584 13 56 40.18 +38 15 26.9 1.7+ 0.7+ 801/HO 1982 06 24.07970 14 03 34.18 +38 02 21.8 1.6- 1.2- 801/HO 1982 06 25.07668 14 10 30.94 +37 47 20.2 0.4- 0.8+ 801/HO 1982 06 27.19014 14 24 34.61 +37 10 43.0 0.1- 0.6+ 801/HO 1982 07 10.18889 15 33 48.05 +32 00 19.4 0.7- 1.4- 707/ev 1982 07 19.10657 16 08 13.49 +27 53 10.3 1.0- 0.0 801/HO 1982 07 23.13571 16 21 27.31 +26 00 48.4 0.4+ 1.5+ 801/HO 1982 08 18.10843 17 27 43.78 +15 01 17.1 1.9- 0.1- 801/HO ( ) -------- Rejected Obs.

Director, Computing Section Syuichi Nakano 1985 July 11

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