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.