SLA_PREC - Precession Matrix (FK5)

From d54fe7c1f704a63824c5bfa0ece65245572e9b27 Mon Sep 17 00:00:00 2001 From: Joseph Hunkeler Date: Wed, 4 Mar 2015 21:21:30 -0500 Subject: Initial commit --- src/slalib/sun67.htx/node152.html | 145 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 145 insertions(+) create mode 100644 src/slalib/sun67.htx/node152.html (limited to 'src/slalib/sun67.htx/node152.html') diff --git a/src/slalib/sun67.htx/node152.html b/src/slalib/sun67.htx/node152.html new file mode 100644 index 0000000..9e5ea39 --- /dev/null +++ b/src/slalib/sun67.htx/node152.html @@ -0,0 +1,145 @@ + + + + +SLA_PREC - Precession Matrix (FK5) + + + + + + + + + + + + +

+ +

+
+ Next: SLA_PRECES - Precession +
+Up: SUBPROGRAM SPECIFICATIONS +
+ Previous: SLA_PREBN - Precession Matrix (FK4) +

SLA_PREC - Precession Matrix (FK5) + +

ACTION: +: Form the matrix of precession between two epochs (IAU 1976, FK5). +
CALL: +: CALL sla_PREC (EP0, EP1, RMATP) +

GIVEN: +

+
+ + + + + + + + + +

EP0	D	beginning epoch
EP1	D	ending epoch

RETURNED: +

+
+ + + + + +

RMATP	D(3,3)	precession matrix

NOTES: +

1. +: The epochs are TDB Julian epochs. +
2. +: The matrix is in the sense: +
v₁ = M $\cdot$ v₀
+ where v₁ is the star vector relative to the + mean equator and equinox of epoch EP1, M is the + $3\times3$ matrix RMATP and + v₀ is the star vector relative to the + mean equator and equinox of epoch EP0. +
3. +: Though the matrix method itself is rigorous, the precession + angles are expressed through canonical polynomials which are + valid only for a limited time span. There are also known + errors in the IAU precession rate. The absolute accuracy + of the present formulation is better than + $0\hspace{-0.05em}^{'\hspace{-0.1em}'}\hspace{-0.4em}.1$ from + 1960AD to 2040AD, better than $1\hspace{-0.05em}^{'\hspace{-0.1em}'}$ from 1640AD to 2360AD, + and remains below $3\hspace{-0.05em}^{'\hspace{-0.1em}'}$ for the whole of the period + 500BC to 3000AD. The errors exceed $10\hspace{-0.05em}^{'\hspace{-0.1em}'}$ outside the + range 1200BC to 3900AD, exceed $100\hspace{-0.05em}^{'\hspace{-0.1em}'}$ outside 4200BC to + 5600AD and exceed $1000\hspace{-0.05em}^{'\hspace{-0.1em}'}$ outside 6800BC to 8200AD. + The SLALIB routine sla_PRECL implements a more elaborate + model which is suitable for problems spanning several + thousand years. +

REFERENCES: +

1. +: Lieske, J.H., 1979. Astr.Astrophys. 73, 282; +equations 6 & 7, p283. +
2. +: Kaplan, G.H., 1981. USNO circular no. 163, pA2. +

+ +

+
+ Next: SLA_PRECES - Precession +
+Up: SUBPROGRAM SPECIFICATIONS +
+ Previous: SLA_PREBN - Precession Matrix (FK4) +

+SLALIB --- Positional Astronomy Library
Starlink User Note 67
P. T. Wallace
12 October 1999
E-mail:ptw@star.rl.ac.uk +

+ + -- cgit