Transformation from J2000.0 equatorial coordinates to ecliptic coordinates. (double precision)
dr,dd double J2000.0 mean RA,Dec (radians) date double TDB (loosely ET) as Modified Julian Date (JD-2400000.5)
*dl,*db double ecliptic longitude and latitude (mean of date, IAU 1980 theory, radians)
slaDcs2c, slaPrec, slaEpj, slaDmxv, slaEcmat, slaDcc2s, slaDranrm, slaDrange P.T.Wallace Starlink 31 October 1993