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diff --git a/math/slalib/doc/mapqk.hlp b/math/slalib/doc/mapqk.hlp new file mode 100644 index 00000000..adfa1f3d --- /dev/null +++ b/math/slalib/doc/mapqk.hlp @@ -0,0 +1,76 @@ +.help mapqk Jun99 "Slalib Package" +.nf + + SUBROUTINE slMAPQ (RM, DM, PR, PD, PX, RV, AMPRMS, RA, DA) + + - - - - - - + M A P Q + - - - - - - + + Quick mean to apparent place: transform a star RA,Dec from + mean place to geocentric apparent place, given the + star-independent parameters. + + Use of this routine is appropriate when efficiency is important + and where many star positions, all referred to the same equator + and equinox, are to be transformed for one epoch. The + star-independent parameters can be obtained by calling the + slMAPA routine. + + If the parallax and proper motions are zero the slMAPZ + routine can be used instead. + + The reference frames and timescales used are post IAU 1976. + + Given: + RM,DM d mean RA,Dec (rad) + PR,PD d proper motions: RA,Dec changes per Julian year + PX d parallax (arcsec) + RV d radial velocity (km/sec, +ve if receding) + + AMPRMS d(21) star-independent mean-to-apparent parameters: + + (1) time interval for proper motion (Julian years) + (2-4) barycentric position of the Earth (AU) + (5-7) heliocentric direction of the Earth (unit vector) + (8) (grav rad Sun)*2/(Sun-Earth distance) + (9-11) barycentric Earth velocity in units of c + (12) sqrt(1-v**2) where v=modulus(ABV) + (13-21) precession/nutation (3,3) matrix + + Returned: + RA,DA d apparent RA,Dec (rad) + + References: + 1984 Astronomical Almanac, pp B39-B41. + (also Lederle & Schwan, Astron. Astrophys. 134, + 1-6, 1984) + + Notes: + + 1) The vectors AMPRMS(2-4) and AMPRMS(5-7) are referred to + the mean equinox and equator of epoch EQ. + + 2) Strictly speaking, the routine is not valid for solar-system + sources, though the error will usually be extremely small. + However, to prevent gross errors in the case where the + position of the Sun is specified, the gravitational + deflection term is restrained within about 920 arcsec of the + centre of the Sun's disc. The term has a maximum value of + about 1.85 arcsec at this radius, and decreases to zero as + the centre of the disc is approached. + + Called: + slDS2C spherical to Cartesian + slDVDV dot product + slDMXV matrix x vector + slDC2S Cartesian to spherical + slDA2P normalize angle 0-2Pi + + P.T.Wallace Starlink 23 August 1996 + + Copyright (C) 1996 Rutherford Appleton Laboratory + Copyright (C) 1995 Association of Universities for Research in Astronomy Inc. + +.fi +.endhelp |