thanks
but how can I know the reference satellite?
Unfortunately there is no satellite exactly on 24.5 degrees.
Your reference satellite is the nearest one to your latitude.
Yours is 24.5...
There are two nearest satellites to this:
Astra 3B @ 23.5°E
Badr 4/5/6/7 @ 26.0°E
You can first receive Astra 3B with the highest signal percentage, then you should "manually" move the dish "one degree" to the "east" side with your own hands. Now your dish is exactly on 24.5 degrees east, which is your reference.