SLA_NUTC
Nutation Components
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ACTION:
- Nutation (SF2001 theory): longitude & obliquity components, and mean obliquity.
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CALL:
CALL sla_NUTC (DATE, DPSI, DEPS, EPS0)
GIVEN:
| DATE | D | TDB (formerly ET) as Modified Julian Date
(JD2400000.5) |
| |
RETURNED:
| DPSI,DEPS | D | nutation in longitude and obliquity (radians) |
| |
| EPS0 | D | mean obliquity (radians) |
| |
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NOTES:
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(1)
- The routine predicts forced nutation (but not free core nutation) plus corrections to
the IAU 1976 precession model.
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(2)
- Earth attitude predictions made by combining the present nutation model with
IAU 1976 precession are accurate to 1 mas (with respect to the ICRS) for a few
decades around 2000.
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(3)
- The slaNutc80 routine is the equivalent of the present routine but using the IAU
1980 nutation theory. The older theory is less accurate, leading to errors as large as
350 mas over the interval 1900-2100, mainly because of the error in the IAU 1976
precession.
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REFERENCES:
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-
(1)
- Shirai, T. & Fukushima, T., Astron.J. 121, 3270-3283 (2001).
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(2)
- Fukushima, T., Astron.Astrophys. 244, L11 (1991).
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(3)
- Simon, J. L., Bretagnon, P., Chapront, J., Chapront-Touze, M., Francou, G. & Laskar,
J., Astron.Astrophys. 282, 663 (1994).