jQuery getJSON method takes authentication header from some other process

Question

There is a JavaScript snippet that does

$.getJSON(....)

Depending how the page loads it sometimes puts "Authentication" header to the request which comes from some other JavaScript code that is not related.

It seems $.getJSON(...) adds it automatically there if its present. I guess it's not possible to remove it with getJSON?

Is it possible to do with .ajax(...) so that I don't sent it?

I tried using .ajax with "beforeSend" by setting it to null and undefined but it will still send the header then, just with empty value.

$.ajax({
          url: 'service.svc/Request',
          type: 'GET',
          dataType: 'json',
          success: function() { alert('hello!'); },
          error: function() { alert('boo!'); },
          beforeSend: setHeader
        });
      });

      function setHeader(xhr) {
        xhr.setRequestHeader('Authorization', 'undefined');
      }