Program NERS_AZELHA  computes azimuth, elevation, and hour angle,
as well as their time derivatives at the moment of time TIM_TAI
for a station with coordinates COO_TRS in the terrestrial
crust-fixed coordinate system. The station observes a source with
coordinates in the barycentric celestial coordinate system RA, DEC.
Both annual and diurnal aberrations are taken into account.
Elevation is computed with respect to the normal to the reference
ellipsoid. Vertical deflection is ignored. Optionally the elevation 
angle can be corrected for refraction.
 
This program can be used only for computation of azimuths, elevations
and hour angles of an object beyond the Solar system, such a as 
a star or a galaxy.
 
Usage: ners_azelha date coo_trs ra dec [none|optic|radio]
 
where date is the date in YYYY.MM.DD_hh:mm:ss.sss format or now,
      coo_trs is the vector of station coordinates in the rotating
              crust-fixed coordinate system in meters,
      ra      is the right ascension of the observed body in rad;
      dec     is the declination of the observed body in rad;
      [none|optic|radio] is optional computation of refraction:
                         none  -- not to account refraction,
                         optic -- to account refraction in optic
                                  range;
                         radio -- to account for refraction in
                                  radio range.
Units: radians for azimuth, elevation angle, and hour angle;
       rad/s for their time derivatives.