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/node147.html | 278 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 278 insertions(+) create mode 100644 src/slalib/sun67.htx/node147.html (limited to 'src/slalib/sun67.htx/node147.html') diff --git a/src/slalib/sun67.htx/node147.html b/src/slalib/sun67.htx/node147.html new file mode 100644 index 0000000..b9d19fb --- /dev/null +++ b/src/slalib/sun67.htx/node147.html @@ -0,0 +1,278 @@ + + + + +SLA_PLANET - Planetary Ephemerides + + + + + + + + + + + + +
+ +next + +up + +previous +
+ Next: SLA_PLANTE - of Planet from Elements +
+Up: SUBPROGRAM SPECIFICATIONS +
+ Previous: SLA_PLANEL - Planet Position from Elements +

+

+

SLA_PLANET - Planetary Ephemerides +   +

+
+
ACTION: +
Approximate heliocentric position and velocity of a planet. +
CALL: +
CALL sla_PLANET (DATE, NP, PV, JSTAT) +

+

+
GIVEN: +
+
+ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
DATEDModified Julian Date (JD-2400000.5)
NPIplanet:
1=Mercury
2=Venus
3=Earth-Moon Barycentre
4=Mars
5=Jupiter
6=Saturn
7=Uranus
8=Neptune
9=Pluto
+

+
RETURNED: +
+
+ + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
PVD(6)heliocentric $[\,x,y,z,\dot{x},\dot{y},\dot{z}\,]$, equatorial, J2000
(AU, AU/s)
JSTATIstatus:
+1 = warning: date outside of range
0 = OK
-1 = illegal NP (outside 1-9)
-2 = solution didn't converge
+

+
NOTES: +
+
1. +
The epoch, DATE, is in the TDB timescale and is in the form +of a Modified Julian Date (JD-2400000.5). +
2. +
The reference frame is equatorial and is with respect to + the mean equinox and ecliptic of epoch J2000. +
3. +
If a planet number, NP, outside the range 1-9 is supplied, an error + status is returned (JSTAT = -1) and the PV vector + is set to zeroes. +
4. +
The algorithm for obtaining the mean elements of the + planets from Mercury to Neptune is due to + J.L.Simon, P.Bretagnon, J.Chapront, + M.Chapront-Touze, G.Francou and J.Laskar (Bureau des + Longitudes, Paris, France). The (completely different) + algorithm for calculating the ecliptic coordinates of + Pluto is by Meeus. +
5. +
Comparisons of the present routine with the JPL DE200 ephemeris + give the following RMS errors over the interval 1960-2025: + 

+ 		 		 position (km) 		 speed (metre/sec) 
+ 
+		 Mercury 		  334 		  0.437
+		 Venus 		  1060 		  0.855
+		 EMB 		  2010 		  0.815
+		 Mars 		  7690 		  1.98
+		 Jupiter 		  71700 		  7.70
+		 Saturn 		  199000 		  19.4
+		 Uranus 		  564000 		  16.4
+		 Neptune 		  158000 		  14.4
+		 Pluto 		  36400 		  0.137        
+
+ From comparisons with DE102, Simon et al. quote the following + longitude accuracies over the interval 1800-2200: + 

+ 		 Mercury 		  $4\hspace{-0.05em}^{'\hspace{-0.1em}'}$ 
+		 Venus 		  $5\hspace{-0.05em}^{'\hspace{-0.1em}'}$ 
+		 EMB 		  $6\hspace{-0.05em}^{'\hspace{-0.1em}'}$ 
+		 Mars 		 $17\hspace{-0.05em}^{'\hspace{-0.1em}'}$ 
+		 Jupiter 		 $71\hspace{-0.05em}^{'\hspace{-0.1em}'}$ 
+		 Saturn 		 $81\hspace{-0.05em}^{'\hspace{-0.1em}'}$ 
+		 Uranus 		 $86\hspace{-0.05em}^{'\hspace{-0.1em}'}$ 
+		 Neptune 		 $11\hspace{-0.05em}^{'\hspace{-0.1em}'}$
+ In the case of Pluto, Meeus quotes an accuracy of + $0\hspace{-0.05em}^{'\hspace{-0.1em}'}\hspace{-0.4em}.6$

+in longitude and + $0\hspace{-0.05em}^{'\hspace{-0.1em}'}\hspace{-0.4em}.2$ in latitude for the period + 1885-2099. +

+For all except Pluto, over the period 1000-3000, + the accuracy is better than 1.5 + times that over 1800-2200. Outside the interval 1000-3000 the + accuracy declines. For Pluto the accuracy declines rapidly + outside the period 1885-2099. Outside these ranges + (1885-2099 for Pluto, 1000-3000 for the rest) a ``date out + of range'' warning status (JSTAT=+1) is returned. +

6. +
The algorithms for (i) Mercury through Neptune and + (ii) Pluto are completely independent. In the Mercury + through Neptune case, the present SLALIB + implementation differs from the original + Simon et al. Fortran code in the following respects: +
    +
  • The date is supplied as a Modified Julian Date rather + a Julian Date (${\rm MJD} = ({\rm JD} - 2400000.5$). +
  • The result is returned only in equatorial + Cartesian form; the ecliptic + longitude, latitude and radius vector are not returned. +
  • The velocity is in AU per second, not AU per day. +
  • Different error/warning status values are used. +
  • Kepler's Equation is not solved inline. +
  • Polynomials in T are nested to minimize rounding errors. +
  • Explicit double-precision constants are used to avoid + mixed-mode expressions. +
  • There are other, cosmetic, changes to comply with + Starlink/SLALIB style guidelines. +
+ None of the above changes affects the result significantly. +
7. +
NP=3 the result is for the Earth-Moon Barycentre. To + obtain the heliocentric position and velocity of the Earth, + either use the SLALIB routine sla_EVP or call sla_DMOON and + subtract 0.012150581 times the geocentric Moon vector from + the EMB vector produced by the present routine. (The Moon + vector should be precessed to J2000 first, but this can + be omitted for modern epochs without introducing significant + inaccuracy.) +
+

+
REFERENCES: +
+
1. +
Simon et al., +Astron. Astrophys. 282, 663 (1994). +
2. +
Meeus, J., + Astronomical Algorithms, Willmann-Bell (1991). +
+
+ +next + +up + +previous +
+ Next: SLA_PLANTE - of Planet from Elements +
+Up: SUBPROGRAM SPECIFICATIONS +
+ Previous: SLA_PLANEL - Planet Position from Elements +

+

+

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