-
ACTION:
- Nutation (IAU 1980 theory): longitude & obliquity components, and mean
obliquity.
-
CALL:
CALL sla_NUTC80 (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:
-
-
(1)
- The IAU 1980 theory used in the present function has errors as large as 350 mas
over the interval 1900-2100, mainly because of the error in the IAU 1976 precession.
For more accurate results, either the corrections published in IERS Bulletin B must
be applied, or the sla_NUTC function can be used. The latter is based upon the more
recent SF2001 nutation theory and is of better than 1 mas accuracy.
-
(2)
- The distinction between the required TDB and TT is always negligible. Moreover,
for all but the most critical applications UTC is adequate.
-
REFERENCES:
-
-
(1)
- Final report of the IAU Working Group on Nutation, chairman P.K.Seidelmann,
1980.
-
(2)
- Kaplan, G.H., 1981. USNO circular no. 163, pA3-6.