midnight_in_china
double t_u = midnight_in_china(rd);
double t = midnight_in_china(rd + 1);
while (winter >= solar_longitude(midnight_in_china(day+1)))
double t = new_moon_atafter(midnight_in_china(rd));
double t = new_moon_before(midnight_in_china(rd));
double t_u = midnight_in_china(rd);