code: def isAboveHorizon(ra, decl, mcRA, lat):
      
      # This function checks if the equatorial distance from 
      # the object to the MC is within its diurnal semi-arc.
      
      dArc, _ = dnarcs(decl, lat)
      dist = abs(angle.closestdistance(mcRA, ra))
      return dist <= dArc/2.0 + 0.0003
docs: Returns if an object's 'ra' and 'decl' 
      is above the horizon at a specific latitude, 
      given the MC's right ascension.