json aquired tumblr feed error, uncaught syntaxerror: unexpected token <

This is my firs开发者_Go百科t question posted here, so I appologize ahead of time if I use bad form.

I have my tumblr blog posts fed into the aside section of my website. Tonight the feed is not displaying on my page. Chrome shows this error:

"Uncaught SyntaxError: Unexpected token < hearthescene.tumblr.com:1"

Here's a snipet of code showing my json request:

$.getJSON(
    "http://hearthescene.tumblr.com/api/read/json?callback=?", 
    function(data) { 
        ...formatting the data for my site....
    }
);

I haven't actually edited anything on the site in a couple days. I was wondering if tumblr has upped the security and I need to do some OAuth authentication or supply an api key?

Any help would be greatly appreciated. Thanks in advance.

---

I needed to add the api_key as such: $.getJSON("http://hearthescene.tumblr.com/api/read/json?/?api_key={my_api_key}&callback=?",