Hearing the door open, Celty was instantly alert and made aware there was a guy walking around. She put the scope on him to scout him out and saw he was carrying his own rifle. 

Quietly she watched him to see if he was any threat. It didn't seem as if he even noticed her, which was good. She had the advantage if it stayed that way. And Celty wasn't planning on giving up her poaition, not this early. 

She continued to watch him, scope fixed on him, monitoring what he did. Judging if he was any real threat to her at all. It just looked like he was bothered by something. Everyone was nowadays, so it want such a surprise to her. But being as cautious as she was, she stayed low to her branch and silent to make sure he didn't catch her.