Py ERFA:docs

- Index
- Modules

### Navigation

- next »
- « previous |
- PyERFA v2.0.0.1 »
- erfa Package »
- nut80

# nut80

erfa.nut80(date1, date2)

  Nutation, IAU 1980 model.

  Parameters
    date1 double array
    date2 double array
  Returns
    dpsi double array
    deps double array

  Notes

  Wraps ERFA function `eraNut80`. The ERFA documentation is:

      - - - - - - - - -
       e r a N u t 8 0
      - - - - - - - - -

      Nutation, IAU 1980 model.

      Given:
         date1,date2   double    TT as a 2-part Julian Date (Note 1)

      Returned:
         dpsi          double    nutation in longitude (radians)
         deps          double    nutation in obliquity (radians)

      Notes:

      1) The TT date date1+date2 is a Julian Date, apportioned in any
         convenient way between the two arguments.  For example,
         JD(TT)=2450123.7 could be expressed in any of these ways,
         among others:

                date1          date2

             2450123.7           0.0       (JD method)
             2451545.0       -1421.3       (J2000 method)
             2400000.5       50123.2       (MJD method)
             2450123.5           0.2       (date & time method)

         The JD method is the most natural and convenient to use in
         cases where the loss of several decimal digits of resolution
         is acceptable.  The J2000 method is best matched to the way
         the argument is handled internally and will deliver the
         optimum resolution.  The MJD method and the date & time methods
         are both good compromises between resolution and convenience.

      2) The nutation components are with respect to the ecliptic of
         date.

      Called:
         eraAnpm      normalize angle into range +/- pi

      Reference:

         Explanatory Supplement to the Astronomical Almanac,
         P. Kenneth Seidelmann (ed), University Science Books (1992),
         Section 3.222 (p111).

      This revision:  2021 May 11

      Copyright (C) 2013-2021, NumFOCUS Foundation.
      Derived, with permission, from the SOFA library.  See notes at end of file.