MPEC 1999-U17: 1998 SM165
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M.P.E.C. 1999-U17 Issued 1999 Oct. 20, 22:32 UT
The Minor Planet Electronic Circulars contain information on unusual
minor planets and routine data on comets. They are published
on behalf of Commission 20 of the International Astronomical Union by the
Minor Planet Center, Smithsonian Astrophysical Observatory,
Cambridge, MA 02138, U.S.A.
BMARSDEN@CFA.HARVARD.EDU or GWILLIAMS@CFA.HARVARD.EDU
URL http://cfa-www.harvard.edu/iau/mpc.html ISSN 1523-6714
1998 SM165
Revision to MPEC 1999-M31
Observations:
J98SG5M C1999 10 04.23456 00 47 43.95 +02 45 07.1 20.1 V 691
J98SG5M C1999 10 04.25626 00 47 43.86 +02 45 05.7 20.0 V 691
J98SG5M C1999 10 04.27714 00 47 43.74 +02 45 05.1 20.3 V 691
J98SG5M C1999 10 06.26694 00 47 33.35 +02 43 49.2 20.7 V 691
J98SG5M C1999 10 06.33747 00 47 32.99 +02 43 46.6 20.7 V 691
J98SG5M C1999 10 08.30053 00 47 22.76 +02 42 32.2 20.9 V 691
J98SG5M C1999 10 08.37080 00 47 22.39 +02 42 29.5 21.0 V 691
J98SG5M C1999 10 10.24099 00 47 12.54 +02 41 19.9 21.0 V 691
J98SG5M C1999 10 10.31078 00 47 12.12 +02 41 16.2 21.3 V 691
Observer details:
691 Steward Observatory, Kitt Peak. Observers R. S. McMillan, J. A. Larsen,
B. May, D. Maggs J.A., N. Danzl. 0.9-m Spacewatch telescope.
First and last observations above in comparison with prediction:
Residuals in seconds of arc (or two decimals in degrees) and reference
991004 691 0.07+ 0.03+ 991010 691 0.07+ 0.03+ MPC 35441
Orbital elements:
1998 SM165
Eccentricity assumed
Epoch 1999 Aug. 10.0 TT = JDT 2451400.5 Marsden
M 26.30338 (2000.0) P Q
n 0.00294732 Peri. 131.67177 +0.70326507 +0.71081573
a 48.1783159 Node 183.10749 -0.70161838 +0.69108368
e 0.3769761 Incl. 13.46069 -0.11467295 +0.13093639
P 334 H 5.8 G 0.15
Residuals in seconds of arc
980916 691 0.1+ 0.1- 980924 691 0.1+ 0.1+ 991006 691 0.3+ 0.1-
980916 691 0.1+ 0.3- 991004 691 0.4- 0.4+ 991008 691 0.9+ 0.1-
980916 691 0.3- 0.0 991004 691 0.0 0.2- 991008 691 0.9+ 0.2-
980924 691 0.1+ 0.1+ 991004 691 0.1- 0.0 991010 691 0.5- 0.8+
980924 691 0.1- 0.1+ 991006 691 0.1+ 0.2- 991010 691 1.2- 0.3-
Ephemeris:
1998 SM165 a,e,i = 48.18, 0.38, 13 q = 30.016
Date TT R. A. (2000) Decl. Delta r Elong. Phase V
1999 10 19 00 46.46 +02 35.9 33.409 34.378 166.3 0.4 21.2
1999 10 29 00 45.64 +02 30.2 33.475 34.387 156.2 0.7 21.2
1999 11 08 00 44.90 +02 25.0 33.569 34.395 146.1 0.9 21.3
1999 11 18 00 44.27 +02 20.7 33.688 34.404 135.8 1.1 21.3
1999 11 28 00 43.77 +02 17.2 33.828 34.412 125.6 1.3 21.3
1999 12 08 00 43.43 +02 14.9 33.987 34.421 115.4 1.5 21.3
1999 12 18 00 43.26 +02 13.7 34.158 34.429 105.2 1.6 21.4
1999 12 28 00 43.27 +02 13.7 34.338 34.438 95.0 1.6 21.4
2000 01 07 00 43.46 +02 14.8 34.520 34.446 84.9 1.6 21.4
2000 01 17 00 43.84 +02 17.2 34.700 34.455 74.8 1.6 21.4
2000 01 27 00 44.40 +02 20.6 34.871 34.464 64.8 1.5 21.4
2000 02 06 00 45.11 +02 25.0 35.030 34.472 54.8 1.3 21.4
2000 02 16 00 45.97 +02 30.2 35.172 34.481 45.0 1.2 21.4
2000 02 26 00 46.96 +02 36.2 35.294 34.489 35.2 0.9 21.4
The general orbit solution is similar to the above, having a = 47.32 AU,
e = 0.356, i = 13.5. However, this solution quickly results in encounters
with Neptune. The adopted solution is in 1:2 resonance with Neptune and
keeps the object more than 23 AU from Neptune over a 14 000-year period.
If the libration is confirmed with further observations, 1998 SM165 would be,
with H = 5.8, the intrinsically brightest known or suspected 1:2 librator, in
comparison with 1996 TR66 (H = 7.5), 1999 KR18 (H = 8.0) and 1997 SZ10
(H = 8.4).
Brian G. Marsden (C) Copyright 1999 MPC M.P.E.C. 1999-U17
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