astern of vs at

astern of

prep
  • behind 

at

prep
  • In, near, or in the general vicinity of a particular place. 

  • (also as at; before dates) On a particular date. 

  • Occupied in (activity). 

  • In a state of. 

  • On the subject of; regarding. 

  • Denotes a price. 

  • Because of. 

  • Bothering, irritating, causing discomfort to 

  • Indicates a position on a scale or in a series. 

  • Indicates a means, method, or manner. 

  • Holding a given speed or rate. 

  • Indicating occurrence in an instant of time or a period of time relatively short in context or from the speaker's perspective. 

  • In the direction of (often in an unfocused or uncaring manner). 

noun
  • The at sign (@). 

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