SLA_ECMAT - Form $\alpha,\delta\rightarrow\lambda,\beta$ Matrix

ACTION:

Form the equatorial to ecliptic rotation matrix (IAU 1980 theory).

CALL:

CALL sla_ECMAT (DATE, RMAT)

GIVEN:

DATE TDB (formerly ET) as Modified Julian Date (JD-2400000.5)

RETURNED:

RMAT rotation matrix

NOTES:

1.

RMAT is matrix M in the expression v_ecl = M$\cdot$v_equ.

2.

The equator, equinox and ecliptic are mean of date.

REFERENCE:

Murray, C.A., Vectorial Astrometry, section 4.3.