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/node163.html | 166 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 166 insertions(+) create mode 100644 src/slalib/sun67.htx/node163.html (limited to 'src/slalib/sun67.htx/node163.html') diff --git a/src/slalib/sun67.htx/node163.html b/src/slalib/sun67.htx/node163.html new file mode 100644 index 0000000..4f6cf04 --- /dev/null +++ b/src/slalib/sun67.htx/node163.html @@ -0,0 +1,166 @@ + + + + +SLA_RCC - Barycentric Coordinate Time + + + + + + + + + + + + +
+ +next + +up + +previous +
+ Next: SLA_RDPLAN - Apparent of Planet +
+Up: SUBPROGRAM SPECIFICATIONS +
+ Previous: SLA_RANORM - Put Angle into Range +

+

+

SLA_RCC - Barycentric Coordinate Time +   +

+
+
CALL: +
D = sla_RCC (TDB, UT1, WL, U, V) +
ACTION: +
The relativistic clock correction TDB-TT, the + difference between proper time + on Earth and coordinate time in the solar system barycentric + space-time frame of reference. The proper time is TT; the + coordinate time is an implementation of TDB. +

+

+
GIVEN: +
+
+ + + + + + + + + + + + + + + + + + + + + +
TDBDcoordinate time (MJD: JD-2400000.5)
UT1Duniversal time (fraction of one day)
WLDclock longitude (radians west)
UDclock distance from Earth spin axis (km)
VDclock distance north of Earth equatorial plane (km)
+

+
RETURNED: +
+
+ + + + + +
sla_RCCDTDB-TT (sec)
+

+
NOTES: +
+
1. +
TDB may be considered to +be the coordinate time in the solar system barycentre frame of +reference, and TT is the proper time given by clocks at mean sea + level on the Earth. +
2. +
The result has a main (annual) sinusoidal term of amplitude + approximately 1.66ms, plus planetary terms up to about + 20$\mu$s, and lunar and diurnal terms up to 2$\mu$s. The + variation arises from the transverse Doppler effect and the + gravitational red-shift as the observer varies in speed and + moves through different gravitational potentials. +
3. +
The argument TDB is, strictly, the barycentric coordinate time; + however, the terrestrial proper time (TT) can in practice be used. +
4. +
The geocentric model is that of Fairhead & Bretagnon (1990), + in its full + form. It was supplied by Fairhead (private communication) + as a Fortran subroutine. A number of coding changes were made to + this subroutine in order + match the calling sequence of previous versions of the present + routine, to comply with Starlink programming standards and to + avoid compilation problems on certain machines. On the supported + computer types, + the numerical results are essentially unaffected by the + changes. The topocentric model is from Moyer (1981) and Murray (1983). + During the interval 1950-2050, the absolute accuracy of the + geocentric model is better than $\pm3$ nanoseconds + relative to direct numerical integrations using the JPL DE200/LE200 + solar system ephemeris. +
5. +
The IAU definition of TDB is that it must differ from TT only by + periodic terms. Though practical, this is an imprecise definition + which ignores the existence of very long-period and secular effects + in the dynamics of the solar system. As a consequence, different + implementations of TDB will, in general, differ in zero-point and + will drift linearly relative to one other. +
+

+
REFERENCES: +
+
1. +
Fairhead, L. & +Bretagnon, P., 1990. Astr.Astrophys. 229, 240-247. +
2. +
Moyer, T.D., 1981. Cel.Mech. 23, 33. +
3. +
Murray, C.A., 1983, Vectorial Astrometry, Adam Hilger. +
+
+ +next + +up + +previous +
+ Next: SLA_RDPLAN - Apparent of Planet +
+Up: SUBPROGRAM SPECIFICATIONS +
+ Previous: SLA_RANORM - Put Angle into Range +

+

+

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