IERS4m

Celestial to Terrestrial transformation (i.e. MJ2000 to ECEF)

Pure MATLAB implementation of the Celestial to Terrestrial coordinate transformation which can be used to convert position, velocity, and acceleration between MJ2000 and ECEF reference frames.
These classes facilitates the CIO based celestial to terrestrial transformation (see figure). The main function is GCRS2ITRS which provides the 3x3 celestial to terrestrial transformation matrix. In order to obtain the necessary EOP information use helper object USNO.m.
There is a detailed write up in the docs/latex folder which explains this transformation in detail as well as explains the matrix formulation implemented in MATLAB. All relevant references are listed in the References section. Select papers are avaliable in the docs/refs folder.
Default 2010 IERS convention.

Tests:
Run unit tests via: UnitTests.exe()

Example Usage:

% date time UTC: 2004/04/06 07:51:28.386
fMJD_UTC = 53101.3274118751;

% init EOP object
eopobj = USNO();

% pull latest EOP data from USNO servers
eopobj.initWithFinalsHttp();

% interpolate EOP information for date and time
[xp,yp,du,dt] = eopobj.getEOP(fMJD_UTC);

% Vallado et al. 2006, AIAA [meters]
X_itrs = [-1033.4793830, 7901.2952754, 6380.3565958]';

% dx,dy = 0 [meters]
X_gcrs = [5102.5089592, 6123.0114033, 6378.1369247]';

% compute the 3x3 transformation matrix
GC2IT = IERS.GCRS2ITRS(fMJD_UTC,dt,du,xp,yp);

% perform the coordinate/position conversion: C -> T
X = GC2IT*X_gcrs;

% compute the error in meters
err = sum(sqrt((X-X_itrs).^2))

References:

IERS 2010
www.iers.org/IERS/EN/Publications/TechnicalNotes/tn36.html

IERS 2003
www.iers.org/IERS/EN/Publications/TechnicalNotes/tn32.html

IERS FTP
ftp://tai.bipm.org/iers/conv2010/chapter5/
ftp://maia.usno.navy.mil/conv2010/chapter5/

SOFA Library

Main:
http://www.iausofa.org

Time Reference Cookbook:
http://www.iausofa.org/2012_0301_C/sofa/sofa_ts_c.pdf

Validation Routines:

C:
http://www.iausofa.org/2012_0301_C/sofa/t_sofa_c.c

FORTRAN:
http://www.iausofa.org/2012_0301_F/sofa/t_sofa_f.for

Tutorial:
www.iausofa.org/publications/sofa_pn.pdf

NOVAS Comparison:
www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA543243

David Vallado, Seago J., Seidelmann P., Implementation Issues
Surrounding the New IAU Reference Systems for Astrodynamics,
AIAA, AAS 06-134, 2006