ltpb¶

erfa.ltpb(epj)[source]¶

Long-term precession matrix, including ICRS frame bias.

Parameters:

epjdouble array

Returns:

rpbdouble array

Notes

Wraps ERFA function eraLtpb. The ERFA documentation is:

- - - - - - - -
 e r a L t p b
- - - - - - - -

Long-term precession matrix, including ICRS frame bias.

Given:
   epj     double         Julian epoch (TT)

Returned:
   rpb     double[3][3]   precession+bias matrix, J2000.0 to date

Notes:

1) The matrix is in the sense

      P_date = rpb x P_ICRS,

   where P_ICRS is a vector in the Geocentric Celestial Reference
   System, and P_date is the vector with respect to the Celestial
   Intermediate Reference System at that date but with nutation
   neglected.

2) A first order frame bias formulation is used, of sub-
   microarcsecond accuracy compared with a full 3D rotation.

3) The Vondrak et al. (2011, 2012) 400 millennia precession model
   agrees with the IAU 2006 precession at J2000.0 and stays within
   100 microarcseconds during the 20th and 21st centuries.  It is
   accurate to a few arcseconds throughout the historical period,
   worsening to a few tenths of a degree at the end of the
   +/- 200,000 year time span.

References:

  Vondrak, J., Capitaine, N. and Wallace, P., 2011, New precession
  expressions, valid for long time intervals, Astron.Astrophys. 534,
  A22

  Vondrak, J., Capitaine, N. and Wallace, P., 2012, New precession
  expressions, valid for long time intervals (Corrigendum),
  Astron.Astrophys. 541, C1

This revision:  2023 March 20

Copyright (C) 2013-2023, NumFOCUS Foundation.
Derived, with permission, from the SOFA library.  See notes at end of file.

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ltpb¶