What precise alignment must occur for the transit method to observe an exoplanet?

Answer

The exoplanet must pass directly in front of its host star from our perspective here on Earth.

The transit method relies entirely on the planet crossing directly between the observer on Earth and the host star, causing a temporary dimming of the star's light.

What precise alignment must occur for the transit method to observe an exoplanet?
measurementastronomyexoplanetsdetection