SLA_EARTH - Approx Earth Pos/Vel

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/node86.html | 124 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 124 insertions(+) create mode 100644 src/slalib/sun67.htx/node86.html (limited to 'src/slalib/sun67.htx/node86.html') diff --git a/src/slalib/sun67.htx/node86.html b/src/slalib/sun67.htx/node86.html new file mode 100644 index 0000000..6507524 --- /dev/null +++ b/src/slalib/sun67.htx/node86.html @@ -0,0 +1,124 @@ + + + + +SLA_EARTH - Approx Earth Pos/Vel + + + + + + + + + + + + +

+ +

+
+ Next: SLA_ECLEQ - Ecliptic to Equatorial +
+Up: SUBPROGRAM SPECIFICATIONS +
+ Previous: SLA_E2H - to Az,El +

SLA_EARTH - Approx Earth Pos/Vel + +

ACTION: +: Approximate heliocentric position and velocity of the Earth +(single precision). +
CALL: +: CALL sla_EARTH (IY, ID, FD, PV) +

GIVEN: +

+
+ + + + + + + + + + + + + +

IY	I	year
ID	I	day in year (1 = Jan 1st)
FD	R	fraction of day

RETURNED: +

+
+ + + + + +

PV	R(6)	Earth $[\,x,y,z,\dot{x},\dot{y},\dot{z}\,]$ (AU, AU s^-1)

NOTES: +

1. +

The date and time is TDB (loosely ET) in a Julian calendar +which has been aligned to the ordinary Gregorian +calendar for the interval 1900 March 1 to 2100 February 28. + The year and day can be obtained by calling sla_CALYD or + sla_CLYD. +

2. +

The Earth heliocentric 6-vector is referred to the + FK4 mean equator and equinox of date. +

3. +

Maximum/RMS errors 1950-2050: +

13/5 $\times10^{-5}$ AU = 19200/7600 km in position +
47/26 $\times10^{-10}$ AU s^-1 = + 0.0070/0.0039 km s^-1 in speed +

4. +

More accurate results are obtainable with the routine sla_EVP. +

+ +

+
+ Next: SLA_ECLEQ - Ecliptic to Equatorial +
+Up: SUBPROGRAM SPECIFICATIONS +
+ Previous: SLA_E2H - to Az,El +

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

+ + -- cgit