of T_1                   |
                     +--------------------------------------+
                                       ...
                     +--------------------------------------+
                     | Coefficient of T_POLYDG              |
                     +--------------------------------------+

                  Where T_n represents the Chebyshev polynomial
                  of the first kind of degree n.
                 
 
   btime          Begin time (seconds past J2000 TDB) of fir