Polaris, the North Star, is close to Declination = +90 degrees.
        If you were standing on the Earth's North Pole, where
        would you see it in the sky? 

                  It would be directly overhead, at  alt = 90 degrees



     If you were standing on the Equator, where would you see
        Polaris in the Sky? 

                  It would be on the northern horizon, at alt = 0 degrees



     The latitude of Rochester is +43 degrees North.
        How far above the horizon is Polaris as seen in Rochester? 

                  alt = 43 degrees above the horizon



     What is the Declination of the southernmost stars
        we can see in Rochester? 

              -90 degrees +  (Rochester latitude)  =  -90 + 43  =  -47 degrees



     Can we see Alpha Centauri from Rochester? 

                  The Declination of Alpha Cen is -60 degrees,
                  so, alas, we can't see it from Rochester.