Use only portion of data

I am looking for another way to use only portion of the following data as it comes in. I was parsing it then just using the sunset portion. My problem is I’m running out of memory. Need simple low memory use way to get the sunset time. I’ve tried substring but couldn’t get it to work. Can someone point me in the right direction… This is the data that I am using

{"results":{"sunrise":"2017-02-11T07:09:19+00:00","sunset":"2017-02-11T17:54:27+00:00","solar_noon":"2017-02-11T12:31:53+00:00","day_length":38708,"civil_twilight_begin":"2017-02-11T06:42:47+00:00","civil_twilight_end":"2017-02-11T18:20:59+00:00","nautical_twilight_begin":"2017-02-11T06:12:19+00:00","nautical_twilight_end":"2017-02-11T18:51:26+00:00","astronomical_twilight_begin":"2017-02-11T05:42:12+00:00","astronomical_twilight_end":"2017-02-11T19:21:33+00:00"},"status":"OK"