def _icrs_to_fk5_matrix():
 eta0 = ((-19.9) / 3600000.0)
 xi0 = (9.1 / 3600000.0)
 da0 = ((-22.9) / 3600000.0)
 m1 = rotation_matrix((- eta0), u'x')
 m2 = rotation_matrix(xi0, u'y')
 m3 = rotation_matrix(da0, u'z')
 return matrix_product(m1, m2, m3)

def _icrs_to_fk5_matrix ( ) : eta0 = ( ( - 19.9 ) / 3600000.0 ) xi0 = ( 9.1 / 3600000.0 ) da0 = ( ( - 22.9 ) / 3600000.0 ) m1 = rotation_matrix ( ( - eta0 ) , u'x' ) m2 = rotation_matrix ( xi0 , u'y' ) m3 = rotation_matrix ( da0 , u'z' ) return matrix_product ( m1 , m2 , m3 )
b-matrix from usno circular 179 .