observatory vs vigil

observatory

noun
  • A lookout (vantage point with a view of the surrounding area) 

  • A place where stars, planets and other celestial bodies are observed, usually through a telescope; also place for observing meteorological or other natural phenomena. 

vigil

noun
  • A period of observation or surveillance at any hour. 

  • A quiet demonstration in support of a cause. 

  • An instance of keeping awake during normal sleeping hours, especially to keep watch or pray. 

  • The eve of a religious festival in which staying awake is part of the ritual devotions. 

How often have the words observatory and vigil occurred in a corpus of books? (source: Google Ngram Viewer )