To check precisely you need a device based ona nautical sextant that measure altiude and the position of the satellite by using a compass built into unit.
Often a satellite can be aimed through the smallest gap between two builds that to the quick glance method isnt apparent.
A satellite is located in elevation and azimuth.Azimuth is easy north is the zero point round to traveling eastward back to north or 360 degrees.
So the astra or sky satellite is 147 degrees from north,over most of the uk,but varies considerably for different countries.
So if somebody as said you cant recieve sky by the have a glance method and you arent satisfied give us a call and we be more precise