SSO Orbital Elements File (December 3, 2009) [sso01 WSDC D-I145, vsn 1.2] Interface Name: SSO Orbital Elements Type of Interface: ASCII text file (fixed-width columns) Written By: SSO Prediction CogE______________________ D. Tholen Read By: SSOID (ssoinit, ssoid)___________________ J. Fowler DESCRIPTION: The SSO Orbital Elements File contains all information needed to compute the heliocentric J2000 position of any solar-system object for which orbit determination has been performed and visual photometric measurements have been made with sufficiant accuracy to satisfy the requirements agreed upon by the SSO science community. This file is prepared offline by the SSO Prediction Cognizant Engineer, David Tholen, and updated versions are provided to WSDC on a regular schedule (TBD once per month). Osculating orbital elements may be represented in a variety of combinations of parameters; the ones used for this file involve parameters that result from computations that always have to be made and therefore are made in advance in order to save CPU cycles during code execution. The file contains ASCII text data arranged in columns of fixed width. The SSOs in this data file are organized by "Type", i.e., the lines of data for a given Type are contiguous in the file. Currently the various Types of SSO are: asteroids, comets, and planets. The order in which Types are included does not matter as long as the entries for each Type are contiguous, but the Type order and number of each Type must be specified with each delivery (see SIS sso04 for more information on Type usage). Description of Columns: Cols Name Description Units Type Format ------- ------ ------------------------------------- ------- ---- -------- 1-35 NAME Standard object ID field [1] - C*35 A35 36-46 Q Perihelion distance AU R*8 F11.7 47-56 ECC Eccentricity - R*8 F10.7 57-92 PV(3) P vector [2] - R*8 3F12.8 93-128 QV(3) Q vector [3] - R*8 3F12.8 129-142 TPERI Time of perihelion passage JD R*8 F14.5 143-152 EPOCH Osculation epoch JD R*8 F10.1 153-158 H Absolute magnitude mag R*8 F6.2 159-164 G Slope parameter [4] - R*8 F6.2 165-173 ERR Orbital element quality estimate - R*8 F9.1 Notes: 1.) The NAME field may contain any combination of MPC number, object name (e.g., Ceres), and (provisional-)designation; comets and planets have no MPC numbers. 2.) The P vector is the unit vector from the Sun toward perihelion in J2000. 3.) The Q unit vector is orthogonal to the P vector in the orbital plane, right-handed about the orbital angular momentum vector. 4.) The slope parameter is used in computing the phase-dependent term in the visual magnitude using the asteroid phase function developed by Bowell, Harris, and Lumme EXAMPLES: (1) Ceres 2.5469018 0.0794747 -0.87733381 +0.33991074 +0.33874191 -0.44438176 -0.84191069 -0.30612291 2454872.66425 2454800.5 3.34 0.12 0.0 (2) Pallas 2.1325055 0.2308781 -0.56667034 +0.81488138 -0.12187316 -0.82110801 -0.54624451 +0.16552514 2454950.51548 2454800.5 4.13 0.11 0.0 (330) Adalberta A910 CB 1.8439304 0.2528876 +0.79998008 +0.58617409 +0.12818659 -0.59467706 +0.74608039 +0.29953839 2455265.75097 2454800.5 12.60 0.15 0.0 (4384) 1990 AA 2.1419956 0.1819428 +0.98697434 -0.06155391 +0.14863633 -0.02941802 +0.83927765 +0.54290663 2455281.06526 2454800.5 12.10 0.15 0.1 2008 XE3 1.1732901 0.5354849 +0.99548332 -0.06339462 +0.07066881 +0.02146377 +0.87539334 +0.48293458 2454640.79597 2454800.5 16.30 0.15 0.0 2066 P-L 2.0881823 0.1822767 +0.99691149 -0.05537032 -0.05569211 +0.07721554 +0.82044945 +0.56648077 2455058.37763 2454800.5 15.30 0.15 0.0 148P/Anderson-LINEAR 2000 SO253 1.7026421 0.5378629 -0.11249621 +0.90866790 +0.40207865 -0.99157894 -0.12878592 +0.01361614 2454609.23878 2454800.5 16.00 0.15 0.0 50P/Arend 1959 N1 1.9239369 0.5294136 +0.71151895 +0.50468959 +0.48890612 -0.70215778 +0.53715919 +0.46736972 2454405.69482 2454800.5 17.00 0.15 0.1 NEAT 2006 K4 3.1890144 0.9980786 +0.00340780 -0.30841073 -0.95124718 -0.55356715 +0.79162374 -0.25864119 2454433.94974 2454800.5 6.00 0.00 0.4 Nishikawa-Takamizawa-Tago 1987 B1 0.8793986 0.9953682 +0.91105025 -0.35711279 -0.20605317 -0.41219392 -0.77783407 -0.47441578 2446860.22543 2454800.5 10.50 0.00 61.9 Mercury 0.3074943 0.2056411 +0.21963258 +0.86978956 +0.44184574 -0.97132197 +0.15267826 +0.18227174 2454757.15380 2454800.5 -0.42 0.00 -2.0 Eris 38.2852025 0.4361667 -0.91283421 -0.35072832 +0.20910128 -0.01482271 -0.48328885 -0.87533546 2546283.77268 2454800.5 -1.20 0.15 0.0