CONAN.utils.ingress_duration
============================

.. py:function:: CONAN.utils.ingress_duration(aR, b, Rp, P, e=0, w=90, tra_occ='tra')

   Compute the ingress duration of transit or occultation in units of P

   :param aR: The scaled semi-major axis of the planet.
   :type aR: float, ufloat, array-like;
   :param b: The impact parameter.
   :type b: float, ufloat, array-like;
   :param Rp: planet-to-star radius ratio.
   :type Rp: float, ufloat, array-like;
   :param P: The period of the planet in days.
   :type P: float, ufloat, array-like;
   :param e: The eccentricity of the orbit.
   :type e: float, ufloat, array-like;
   :param w: The argument of periastron in degrees.
   :type w: float, ufloat, array-like;
   :param tra_occ: select duration of transit (tra) or occultation (occ)
   :type tra_occ: str;

   :returns: **Tdur** -- The ingress duration in days (same unit as P).
   :rtype: array-like;