JEphem Presentation Ephemeris SkyMap Curve Informatic Library Download Glossary About | |
JEphem Ephemeris trail Testing JEphem |
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Testing VSOP87 |
It is possible to check the results of JEphem computation thanks to the test files given in the BDL's FTP site.
They give a file containing for each version of VSOP87 theory and for each planet, the results of the computation at 10 different dates. I wrote a class, TestVSOP87.java (cf javadoc or , source code) which reads the results found in the test file and compares it to results of JEphem. This class has a method, testJEphemPrecision() , which produces an HTML page containing the results of the tests.
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testJEphemPrecision()
, can produce 3 kinds of outputs : intermediary results (Detailed tests and Difference tables) an a Summary
testJEphemPrecision()
in separate pages : Tests for full precision version and Tests for truncated version .
JD = 2122820.0 19/12/1099 12h TDB | ||||||||
Variables | ||||||||
e r |
BDL | |||||||
JEphem full | ||||||||
|J. full - BDL| | ||||||||
e n |
BDL | |||||||
JEphem full | ||||||||
|J. full - BDL| | ||||||||
a r |
BDL | |||||||
JEphem full | ||||||||
|J. full - BDL| | ||||||||
a r |
BDL | |||||||
JEphem full | ||||||||
|J. full - BDL| | ||||||||
u p |
BDL | |||||||
JEphem full | ||||||||
|J. full - BDL| | ||||||||
a t |
BDL | |||||||
JEphem full | ||||||||
|J. full - BDL| | ||||||||
r a |
BDL | |||||||
JEphem full | ||||||||
|J. full - BDL| | ||||||||
e p |
BDL | |||||||
JEphem full | ||||||||
|J. full - BDL| |
0,0000000001 | 0,0000000001 | 0,0000000006 | 0,0000000006 | 0,0000000001 | 0,0000000001 | 0,0000000001 | 0,0000000001 | |
0,0000000008 | 0,0000000011 | 0,0000000004 | 0,0000000014 | 0,0000000000 | 0,0000000003 | 0,0000000003 | 0,0000000004 | |
0,0000000000 | 0,0000000018 | 0,0000000005 | 0,0000000019 | 0,0000000003 | 0,0000000003 | 0,0000000004 | 0,0000000006 | |
0,0000000008 | 0,0000000001 | 0,0000000005 | 0,0000000009 | 0,0000000000 | 0,0000000000 | 0,0000000003 | 0,0000000003 | |
0,0000000006 | 0,0000000001 | 0,0000000001 | 0,0000000006 | 0,0000000002 | 0,0000000000 | 0,0000000000 | 0,0000000002 | |
0,0000000006 | 0,0000000001 | 0,0000000012 | 0,0000000013 | 0,0000000003 | 0,0000000003 | 0,0000000001 | 0,0000000004 | |
0,0000000018 | 0,0000000023 | 0,0000000007 | 0,0000000030 | 0,0000000001 | 0,0000000005 | 0,0000000001 | 0,0000000005 | |
0,0000000023 | 0,0000000001 | 0,0000000012 | 0,0000000026 | 0,0000000004 | 0,0000000001 | 0,0000000005 | 0,0000000006 | |
0,0000000010 | 0,0000000002 | 0,0000000007 | 0,0000000012 | 0,0000000002 | 0,0000000000 | 0,0000000001 | 0,0000000002 | |
0,0000000011 | 0,0000000007 | 0,0000000009 | 0,0000000016 | 0,0000000001 | 0,0000000001 | 0,0000000000 | 0,0000000002 | |
Delta max | 0,0000000023 | 0,0000000023 | 0,0000000012 | 0,0000000030 | 0,0000000004 | 0,0000000005 | 0,0000000005 | 0,0000000006 |
The geocentric angular error is calculated in the "worst case", when the distance Earth - planet is minimal. For distance EP, formulae 2.1 and 2.2 of previous page were used. Figure 1 illustrates the situation for an outer and an inner planet. |
delta max |
angular error |
delta max | |
Mercury | 0,0000000030 au 0,449 km |
0,0000000006 au/s 0,001 m/s - 0,004 km/h |
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Venus | 0,0000000020 au 0,306 km |
0,0000000002 au/s 0,000 m/s - 0,001 km/h |
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Earth | 0,0000000031 au 0,461 km |
0,0000000003 au/s 0,001 m/s - 0,002 km/h |
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Mars | 0,0000000034 au 0,501 km |
0,0000000001 au/s 0,000 m/s - 0,001 km/h |
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Jupiter | 0,0000000022 au 0,332 km |
0,0000000001 au/s 0,000 m/s - 0,001 km/h |
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Saturn | 0,0000000045 au 0,673 km |
0,0000000001 au/s 0,000 m/s - 0,001 km/h |
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Uranus | 0,0000000031 au 0,461 km |
0,0000000001 au/s 0,000 m/s - 0,001 km/h |
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Neptune | 0,0000000055 au 0,818 km |
0,0000000001 au/s 0,000 m/s - 0,001 km/h |
Positions | Velocities | ||
Norm of delta max |
Geocentric angular error |
Norm of delta max | |
Mercury | 0,0000059206 au 885,705 km |
2,002 " | 0,0000008551 au/s 1,512 m/s - 5,444 km/h |
Venus | 0,0000004678 au 69,980 km |
0,345 " | 0,0000000241 au/s 0,043 m/s - 0,154 km/h |
Earth | 0,0000031916 au 477,457 km |
0,658 " | 0,0000002851 au/s 0,504 m/s - 1,815 km/h |
Mars | 0,0000045381 au 678,897 km |
1,800 " | 0,0000000777 au/s 0,137 m/s - 0,495 km/h |
Jupiter | 0,0000427466 au 6 394,799 km |
2,099 " | 0,0000002861 au/s 0,506 m/s - 1,821 km/h |
Saturn | 0,0001597247 au 23 894,479 km |
3,853 " | 0,0000002563 au/s 0,453 m/s - 1,632 km/h |
Uranus | 0,0003595850 au 53 793,148 km |
4,071 " | 0,0000001920 au/s 0,340 m/s - 1,222 km/h |
Neptune | 0,0003224473 au 48 237,428 km |
2,285 " | 0,0000001973 au/s 0,349 m/s - 1,256 km/h |