OAA computing section circular NK 1296 P/Spacewatch = (60558) 2000 EC98
The following improved orbital elements, by S. Nakano, are from 115 observations 1979 to 2006. Perturbations by Mercury to Neptune and three minor planets, Ceres, Pallas and Vesta, were taken into account. The mean residual is +/- 0.66 arc second. Orbit was computed including the following unconfirmed observations found by author. The comet will be numbered as 174P. s387ac C2001 04 16.13311011 20 46.261+04 04 41.17 21.50Ve 645 s387ac C2001 04 16.13658211 20 46.233+04 04 41.63 22.45 e 645 Epoch = 2015 Apr. 8.0 TT T = 2015 Apr. 22.45521 +/- 0.01595 (m.e.) TT Peri. = 162.93315 +/- 0.00024 Node = 173.33474 +/- 0.00021 (2000.0) Inc. = 4.34434 +/- 0.00008 q = 5.8170375 +/- 0.0000169 AU e = 0.4554614 +/- 0.0000012 a = 10.6825064 +/- 0.0000037 AU n' = 0.02822892 +/- 0.00000001 P = 34.915 +/- 0.0000180 years T = 1980 Mar. 6.45631 TT Epoch = 1980 Mar. 22.0 TT Peri. = 162.56109 e = 0.4560731 Node = 173.42372 (2000.0) a = 10.6785128 AU Inc. = 4.34217 n'= 0.02824476 q = 5.8083302 AU P = 34.895 years The predicted orbit for the 2050 return is as follows: T = 2050 May 18.52759 TT Epoch = 2050 June 3.0 TT Peri. = 162.62207 e = 0.4539008 Node = 172.87815 (2000.0) a = 10.7531167 AU Inc. = 4.33896 n'= 0.02795133 q = 5.8722682 AU P = 35.262 years The following residuals in seconds of arc are from the above orbital elements: Date Code Residual(") Date Code Residual(") Date Code Residual(") 1979/ 010224 621 0.4+ 0.2- 030225 621 0.2- 0.4- 790923 413 0.0 0.5+ 010225 621 0.1- 0.4+ 030226 621 0.8+ 0.2- 790923 413 0.4+ 2.0- 010225 621 0.5+ 0.8+ 030226 621 0.1+ 1.0- 1985/ 010314 304 0.2+ 0.0 030407 691 1.1- 0.3+ 850914 413 0.2- 2.3+ 010314 304 0.1+ 0.1- 030407 691 0.8- 0.1- 2000/ 010416 645 0.1- 0.4- 030407 691 0.4- 0.3+ 000205 691 0.4+ 0.2- 010416 645 0.0 0.2- 030506 291 0.5- 0.8- 000205 691 0.3+ 0.1+ 010423 691 0.6+ 1.4+ 030506 291 0.3- 0.3- 000205 691 0.1+ 0.1- 010423 691 0.5+ 0.6+ 030506 291 0.7- 0.5- 000303 691 0.5- 0.7- 010423 691 0.0 1.3+ 030602 309 0.4+ 0.2- 000303 691 0.2+ 0.3- 011217 304 0.5- 0.1- 030602 309 0.4+ 0.2- 000303 691 0.2- 0.5- 011217 304 0.4- 0.2- 030602 309 0.3+ 0.3- 000304 691 1.1- 0.1- 2002/ 030602 309 0.3+ 0.3- 000304 691 0.7- 0.1+ 020114 950 0.5- 0.1- 030602 309 0.3+ 0.2- 000304 691 0.3+ 0.4+ 020114 950 0.5- 0.2- 030603 309 0.6- 0.6- 000309 691 0.2+ 0.3+ 020114 950 0.4- 0.2- 030603 309 0.6- 0.6- 000309 691 0.5+ 0.2+ 020216 291 0.3- 0.2+ 030603 309 0.6- 0.6- 000309 691 0.4+ 1.3+ 020216 291 1.2+ 0.4+ 030603 309 0.5- 0.6- 000312 691 0.1- 0.7- 020216 291 0.4- 0.1- 030603 309 0.6- 0.7- 000312 691 0.4+ 0.6- 020313 291 0.2- 0.0 2004/ 000312 691 0.4+ 0.2- 020313 291 0.0 0.1- 040414 691 0.7- 0.6- 000313 413 0.0 0.1- 020313 291 0.2+ 0.3- 040414 691 0.6- 1.0- 000313 413 0.2- 0.3- 020401 246 1.0+ 1.1- 040414 691 0.9- 0.6- 000314 691 0.9+ 0.4- 020401 246 1.3+ 1.1+ 040526 304 1.0- 0.5- 000314 691 0.4- 1.0+ 020401 621 0.7+ 0.6- 040526 304 1.0- 0.4- 000314 691 0.0 0.6+ 020401 621 0.5- 0.5- 2006/ 000329 568 0.3+ 0.0 020402 246 0.8+ 1.4- 060107 349 0.9+ 0.7+ 000329 568 0.2+ 0.0 020402 246 1.0+ 0.0 060107 349 0.8+ 0.5+ 000329 568 0.3+ 0.1+ 020403 621 0.5+ 0.3+ 060107 349 1.0+ 0.6+ 000404 691 0.4- 0.5+ 020403 621 0.0 0.7+ 060108 349 1.6+ 1.7+ 000404 691 0.2- 0.8+ 020407 291 1.0- 0.8- 060108 349 1.2+ 1.8+ 000404 691 0.3+ 0.4- 020407 291 0.6- 0.8+ 060108 349 1.6+ 1.6+ 001123 695 0.0 0.7+ 020407 291 0.1+ 0.1+ 060108 300 (0.9- 2.1+) 001123 695 0.2- 0.7+ 2003/ 060108 300 0.4- 1.2+ 2001/ 030110 621 0.1- 0.5- 060108 300 0.1+ 1.9+ 010215 621 0.4- 0.1+ 030110 621 0.2- 1.0+ 060109 235 (0.1+ 2.4+) 010215 621 0.5- 0.7+ 030110 621 0.0 0.5- 060109 H06 1.0- 0.8+ 010216 621 0.5+ 0.7- 030110 621 0.7- 1.2- 060109 D89 1.2+ 0.7+ 010219 950 0.3- 0.1- 030210 621 0.1+ 0.9- 060109 D89 (2.6+ 0.9+) 010219 950 0.3- 0.2- 030210 621 0.1- 0.3+ 060114 213 0.1+ 0.7+ 010221 688 1.4+ 0.2- 030224 621 1.1- 0.8+ 060114 213 0.2+ 0.7+ 010221 688 0.2+ 0.7- 030224 621 0.7- 0.0 060114 213 0.1- 0.6+ ( ) -------- Rejected Obs.
Director, Computing Section Syuichi Nakano 2006 Jan. 15