================================================================================ ================================================================================ 8888888b. 888 888 d888 888888888 888 Y88b 888 888 d8888 888 888 888 888 888 888 888 888 d88P 8888888888 888 8888888b. 8888888P" 888 888 888 "Y88b 888 888 888 888 888 888 888 888 888 Y88b d88P 888 888 888 8888888 "Y8888P" ================================================================================ ================================================================================ CONTENTS : This file provides the ephemeris of the ninth Saturnian satellite: Phoebe AUTHOR : J. Desmars INSTITUTE : IMCCE E-MAIL : desmars@imcce.fr REFERENCE : Desmars J, Li S.N., Tajeddine R., Peng Q.Y., Tang Z.H. Phoebe's Orbit from ground-based and space-based observations A&A 553, 36D, 10p, 2013 ================================================================================ FILES ----- - README.txt : This file - ph15.dat : Chebychev polynomia - r-ph.f90 : Fortran subroutines used to compute ephemeris - test.f90 : Fortran program to test the computation ================================================================================ README FILE: ------------ This ephemeris of Phoebe is based on a numerical model fitted to the observations dispatched from 1898 to 2014. This ephemeris is available for the period [1875/07/01:2022/06/30] and through Chebychev polynomia (ph15.dat) readable with the Fortran subroutines contained in r-ph.f90. ================================================================================ FORTRAN SUBROUTINES ------------------- header : Read the header of ph15.dat to load information such as degree of polynomia or period of validity Out: - nc : degree of polynomia - ni : number of intervals - a : first date of validity - b : last date of validity load : Load the coefficients of Chebychev polynomia In : - nc : degree of polynomia (given by header) - ni : number of intervals (given by header) Out: - cf : coefficients - dat : limit period of intervals pos_ph12: Compute the position and velocity for a specific date (in TDB) In : - a : first date of validity (given by header) - b : last date of validity (given by header) - nc : degree of polynomia (given by header) - ni : number of intervals (given by header) - cf : coefficients (given by load) - dat : period of intervals (given by load) - t : time in Julian Day(TDB) (given by user) Out: - x : 6-dimension vector position-velocity ================================================================================ UNITS: ------ Positions and velocities are delivered in au and au/day. ================================================================================ EXAMPLE: --------- Computation of test program should provide: DJ = 2450000.500 x = -0.0565315991521 0.0683541665349 0.0384513619268 y = 0.0006274528080 0.0005863229898 0.0001848040392 DJ = 2450010.500 x = -0.0500077685742 0.0738917050575 0.0401185066835 y = 0.0006760300996 0.0005207178864 0.0001485809598 DJ = 2450020.500 x = -0.0430362381452 0.0787601500517 0.0414224858221 y = 0.0007170347454 0.0004525975975 0.0001122080648 DJ = 2450030.500 x = -0.0356914954854 0.0829370089715 0.0423628543553 y = 0.0007507122167 0.0003824804947 0.0000758900642 DJ = 2450040.500 x = -0.0280456595218 0.0864045936164 0.0429410513960 y = 0.0007772891303 0.0003108114798 0.0000398004898 DJ = 2450050.500 x = -0.0201687110819 0.0891493549543 0.0431601262402 y = 0.0007969654703 0.0002379757927 0.0000040889789 DJ = 2450060.500 x = -0.0121287880118 0.0911613526180 0.0430245339092 y = 0.0008099092464 0.0001643119401 -0.0000311119890 DJ = 2450070.500 x = -0.0039925210707 0.0924338483511 0.0425399926980 y = 0.0008162533798 0.0000901236760 -0.0000656813027 DJ = 2450080.500 x = 0.0041746055080 0.0929630123083 0.0417133964504 y = 0.0008160940137 0.0000156907545 -0.0000995041242 DJ = 2450090.500 x = 0.0123078794675 0.0927477347517 0.0405527759854 y = 0.0008094894147 -0.0000587208587 -0.0001324670901 DJ = 2450100.500 x = 0.0203429817690 0.0917895403942 0.0390673084757 y = 0.0007964600304 -0.0001328486525 -0.0001644536092 ================================================================================ J.Desmars (2016/01/11) ================================================================================