Cats

I remember during last year in fall I sat near my open window with the curtain down, but I wanted fresh air so I pulled it aside then saw an orange cat starring straight at me while sniffing through the screen, tried to be silent and not move, but he or she left either way. Another unusal event which has been occuring more often at night I would hear a very loud cry judging by the sound it appears to be from a cat, one time I heard it during the afternoon and decided to check it out and went outside, but nothing would be there. I do own a cat and perhaps might be the reason to attract other cats, but I rarely let my cat go outside and when I do he won't be out for more than ten minutes. Any ideas?