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diff --git a/math/slalib/doc/planel.hlp b/math/slalib/doc/planel.hlp new file mode 100644 index 00000000..c5a0f02f --- /dev/null +++ b/math/slalib/doc/planel.hlp @@ -0,0 +1,96 @@ +.help planel Jun99 "Slalib Package" +.nf + + SUBROUTINE slPLNE (DATE, JFORM, EPOCH, ORBINC, ANODE, PERIH, + : AORQ, E, AORL, DM, PV, JSTAT) + + - - - - - - - + P L N L + - - - - - - - + + Heliocentric position and velocity of a planet, asteroid or comet, + starting from orbital elements. + + Given: + DATE d date, Modified Julian Date (JD - 2400000.5) + JFORM i choice of element set (1-3; Note 3) + EPOCH d epoch of elements (TT MJD) + ORBINC d inclination (radians) + ANODE d longitude of the ascending node (radians) + PERIH d longitude or argument of perihelion (radians) + AORQ d mean distance or perihelion distance (AU) + E d eccentricity + AORL d mean anomaly or longitude (radians, JFORM=1,2 only) + DM d daily motion (radians, JFORM=1 only) + + Returned: + PV d(6) heliocentric x,y,z,xdot,ydot,zdot of date, + J2000 equatorial triad (AU,AU/s) + JSTAT i status: 0 = OK + -1 = illegal JFORM + -2 = illegal E + -3 = illegal AORQ + -4 = illegal DM + -5 = numerical error + + Called: slELUE, slUEPV + + Notes + + 1 DATE is the instant for which the prediction is required. It is + in the TT timescale (formerly Ephemeris Time, ET) and is a + Modified Julian Date (JD-2400000.5). + + 2 The elements are with respect to the J2000 ecliptic and equinox. + + 3 Three different element-format options are available: + + Option JFORM=1, suitable for the major planets: + + EPOCH = epoch of elements (TT MJD) + ORBINC = inclination i (radians) + ANODE = longitude of the ascending node, big omega (radians) + PERIH = longitude of perihelion, curly pi (radians) + AORQ = mean distance, a (AU) + E = eccentricity, e (range 0 to <1) + AORL = mean longitude L (radians) + DM = daily motion (radians) + + Option JFORM=2, suitable for minor planets: + + EPOCH = epoch of elements (TT MJD) + ORBINC = inclination i (radians) + ANODE = longitude of the ascending node, big omega (radians) + PERIH = argument of perihelion, little omega (radians) + AORQ = mean distance, a (AU) + E = eccentricity, e (range 0 to <1) + AORL = mean anomaly M (radians) + + Option JFORM=3, suitable for comets: + + EPOCH = epoch of perihelion (TT MJD) + ORBINC = inclination i (radians) + ANODE = longitude of the ascending node, big omega (radians) + PERIH = argument of perihelion, little omega (radians) + AORQ = perihelion distance, q (AU) + E = eccentricity, e (range 0 to 10) + + 4 Unused elements (DM for JFORM=2, AORL and DM for JFORM=3) are + not accessed. + + 5 The reference frame for the result is with respect to the mean + equator and equinox of epoch J2000. + + 6 The algorithm was originally adapted from the EPHSLA program of + D.H.P.Jones (private communication, 1996). The method is based + on Stumpff's Universal Variables. + + Reference: Everhart, E. & Pitkin, E.T., Am.J.Phys. 51, 712, 1983. + + P.T.Wallace Starlink 18 March 1999 + + Copyright (C) 1999 Rutherford Appleton Laboratory + Copyright (C) 1995 Association of Universities for Research in Astronomy Inc. + +.fi +.endhelp |