SSO ssoinit/ssoid Intermediate File (June 5, 2009) [sso2 WSDC D-I146, vsn 1.1] Interface Name: SSO ssoinit/ssoid Intermediate File Type of Interface: ASCII text file (pairs of alternating fixed-width columns) Written By: SSOID (ssoinit)__________________________ J. Fowler Read By: SSOID (ssoid)____________________________ J. Fowler DESCRIPTION: The SSO ssoinit/ssoid Intermediate File contains all information needed to compute the heliocentric J2000 position of the solar-system objects found by ssoinit to lie in the scan swath, which is the region on the sky within (default) 2 degrees of the instrument boresight during an entire science scan (see the SSOID SDS, WSDC D-D017). In addition to the orbital elements defined in SIS sso01 (WSDC D-I145), this file contains information computed by the ssoinit module that can be used to speed up execution of the ssoid module. The extra information is passed as a companion ASCII text line for each line of sso01 orbital-element data. Thus the information for a single SSO consists of a pair of ASCII text lines; the first is exactly the same as those defined in SIS sso01; the second is defined in this SIS. Description of Columns of the Second Line in Each Pair: Cols Name Description Units Type Format ------- ------ ------------------------------------- ------- ---- -------- 1-16 Xsc X component of unit vector [1] [2] - R*8 1pD16.8 17-32 Ysc Y component of unit vector [1] [2] - R*8 1pD16.8 33-48 Zsc Z component of unit vector [1] [2] - R*8 1pD16.8 49-64 DTN Mean Motion [2] rad/day R*8 1pD16.8 65-80 TDist Topocentric Distance [2] AU R*8 1pD16.8 81-96 EccAnom2 Eccentric Anomaly [2] [3] rad R*8 1pD16.8 97-98 Type Type ID [4] - C*1 1x,A1 Notes: 1.) The unit vector points from the spacecraft to the SSO; this is used by ssoid in a coarse dot-product test to eliminate quickly the vast majority of SSOs that are in the scan swath but not in the frameset being processed. 2.) The epoch is the second of three processed by ssoinit; this is intended to be approximately near the center point of the scan. 3.) This value for the eccentric anomaly is currently not used in the ssoid module; it could be used to start the iterative solution of Kepler's equation, but for most objects this iteration converges so quickly that it was decided not to alter D. Tholen's code to use it. 4.) The Type ID labels each SSO according to whether it is a numbered asteroid, unnumbered asteroid, comet, etc.; see SIS sso04 for details. EXAMPLES of Line Pairs (second line of each pair is defined by this SIS, first line by sso01): (1057) Wanda 1925 QB 2.1742784 0.2486700 0.98040763 0.15034713 0.12726596 -0.18753693 0.91007604 0.36958287 2453275.04172 2454800.5 10.96 0.15 0.0 8.49385923D-01 4.72926258D-01 2.34274001D-01 3.49425672D-03 1.99647808D+00 6.35400956D-01 A (1130) Skuld 1929 RC 1.7880781 0.1976600 0.86449885 -0.47384759 -0.16766095 0.50213598 0.79932110 0.33006853 2453768.75281 2454800.5 12.10 0.15 0.1 8.37643914D-01 5.08170960D-01 2.00287167D-01 5.17058142D-03 1.78588198D+00 1.37732056D+00 A (1165) Imprinetta 1930 HM 2.4541328 0.2146300 0.51089052 -0.84991584 -0.12897265 0.85497062 0.48673521 0.17920402 2454744.10646 2454800.5 10.30 0.15 0.0 8.53168569D-01 5.10276054D-01 1.08266992D-01 3.11419507D-03 2.95357848D+00 1.67307261D+00 A 2003 FR120 2.1796900 0.1589800 -0.79518303 -0.56826161 -0.21157194 0.60561997 -0.76163078 -0.23052767 2454370.54652 2454800.5 16.70 0.15 0.1 8.45716095D-01 5.09877999D-01 1.57444319D-01 4.12286230D-03 2.71656590D+00 -2.85558777D+00 U SOHO 2000 Y6 0.0224365 0.9999915 +0.00940618 -0.45099658 +0.89247611 +0.64063357 +0.68801200 +0.34092246 2451899.60457 2454800.5 75.00 0.00 -2.0 4.70809807D-02 4.59655620D-01 -8.86848405D-01 1.26846114D-07 2.43442930D+01 1.36026087D-01 C