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diff --git a/math/slalib/doc/pertel.hlp b/math/slalib/doc/pertel.hlp new file mode 100644 index 00000000..c1685eca --- /dev/null +++ b/math/slalib/doc/pertel.hlp @@ -0,0 +1,121 @@ +.help pertel Jun99 "Slalib Package" +.nf + + SUBROUTINE slPRTL (JFORM, DATE0, DATE1, + : EPOCH0, ORBI0, ANODE0, PERIH0, AORQ0, E0, AM0, + : EPOCH1, ORBI1, ANODE1, PERIH1, AORQ1, E1, AM1, + : JSTAT) + + - - - - - - - + P R T L + - - - - - - - + + Update the osculating orbital elements of an asteroid or comet by + applying planetary perturbations. + + Given (format and dates): + JFORM i choice of element set (2 or 3; Note 1) + DATE0 d date of osculation (TT MJD) for the given elements + DATE1 d date of osculation (TT MJD) for the updated elements + + Given (the unperturbed elements): + EPOCH0 d epoch (TT MJD) of the given element set (Note 2) + ORBI0 d inclination (radians) + ANODE0 d longitude of the ascending node (radians) + PERIH0 d argument of perihelion (radians) + AORQ0 d mean distance or perihelion distance (AU) + E0 d eccentricity + AM0 d mean anomaly (radians, JFORM=2 only) + + Returned (the updated elements): + EPOCH1 d epoch (TT MJD) of the updated element set (Note 2) + ORBI1 d inclination (radians) + ANODE1 d longitude of the ascending node (radians) + PERIH1 d argument of perihelion (radians) + AORQ1 d mean distance or perihelion distance (AU) + E1 d eccentricity + AM1 d mean anomaly (radians, JFORM=2 only) + + Returned (status flag): + JSTAT i status: +102 = warning, distant epoch + +101 = warning, large timespan ( > 100 years) + +1 to +8 = coincident with major planet (Note 6) + 0 = OK + -1 = illegal JFORM + -2 = illegal E0 + -3 = illegal AORQ0 + -4 = internal error + -5 = numerical error + + Notes: + + 1 Two different element-format options are available: + + Option JFORM=2, suitable for minor planets: + + EPOCH = epoch of elements (TT MJD) + ORBI = 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 + AM = mean anomaly M (radians) + + Option JFORM=3, suitable for comets: + + EPOCH = epoch of perihelion (TT MJD) + ORBI = 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 + + 2 DATE0, DATE1, EPOCH0 and EPOCH1 are all instants of time in + the TT timescale (formerly Ephemeris Time, ET), expressed + as Modified Julian Dates (JD-2400000.5). + + DATE0 is the instant at which the given (i.e. unperturbed) + osculating elements are correct. + + DATE1 is the specified instant at which the updated osculating + elements are correct. + + EPOCH0 and EPOCH1 will be the same as DATE0 and DATE1 + (respectively) for the JFORM=2 case, normally used for minor + planets. For the JFORM=3 case, the two epochs will refer to + perihelion passage and so will not, in general, be the same as + DATE0 and/or DATE1 though they may be similar to one another. + + 3 The elements are with respect to the J2000 ecliptic and equinox. + + 4 Unused elements (AM0 and AM1 for JFORM=3) are not accessed. + + 5 See the slPRTE routine for details of the algorithm used. + + 6 This routine is not intended to be used for major planets, which + is why JFORM=1 is not available and why there is no opportunity + to specify either the longitude of perihelion or the daily + motion. However, if JFORM=2 elements are somehow obtained for a + major planet and supplied to the routine, sensible results will, + in fact, be produced. This happens because the slPRTE routine + that is called to perform the calculations checks the separation + between the body and each of the planets and interprets a + suspiciously small value (0.001 AU) as an attempt to apply it to + the planet concerned. If this condition is detected, the + contribution from that planet is ignored, and the status is set to + the planet number (Mercury=1,...,Neptune=8) as a warning. + + Reference: + + Sterne, Theodore E., "An Introduction to Celestial Mechanics", + Interscience Publishers Inc., 1960. Section 6.7, p199. + + Called: slELUE, slPRTE, slUEEL + + P.T.Wallace Starlink 14 March 1999 + + Copyright (C) 1999 Rutherford Appleton Laboratory + Copyright (C) 1995 Association of Universities for Research in Astronomy Inc. + +.fi +.endhelp |