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.help ampqk Jun99 "Slalib Package"
.nf
SUBROUTINE slAMPQ (RA, DA, AMPRMS, RM, DM)
- - - - - -
A M P Q
- - - - - -
Convert star RA,Dec from geocentric apparent to mean place
The mean coordinate system is the post IAU 1976 system,
loosely called FK5.
Use of this routine is appropriate when efficiency is important
and where many star positions are all to be transformed for
one epoch and equinox. The star-independent parameters can be
obtained by calling the slMAPA routine.
Given:
RA d apparent RA (radians)
DA d apparent Dec (radians)
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) ABV: barycentric Earth velocity in units of c
(12) sqrt(1-v**2) where v=modulus(ABV)
(13-21) precession/nutation (3,3) matrix
Returned:
RM d mean RA (radians)
DM d mean Dec (radians)
References:
1984 Astronomical Almanac, pp B39-B41.
(also Lederle & Schwan, Astron. Astrophys. 134,
1-6, 1984)
Notes:
1) The accuracy is limited by the routine slEVP, called
by slMAPA, which computes the Earth position and
velocity using the methods of Stumpff. The maximum
error is about 0.3 milliarcsecond.
2) Iterative techniques are used for the aberration and
light deflection corrections so that the routines
slAMP (or slAMPQ) and slMAP (or slMAPQ) are
accurate inverses; even at the edge of the Sun's disc
the discrepancy is only about 1 nanoarcsecond.
Called: slDS2C, slDIMV, slDVDV, slDVN, slDC2S,
slDA2P
P.T.Wallace Starlink 21 June 1993
Copyright (C) 1995 Rutherford Appleton Laboratory
Copyright (C) 1995 Association of Universities for Research in Astronomy Inc.
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.endhelp
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