90

Wait ! Usually ascent for ISS is 42° so why is there such a difference? Because the real calculation is a bit more complicated: you have to take in account hte earth's rotation, final orbital speed, etc. etc. This said if you launch with such heading you'll be off by only 3° Relative Inc, a 28 second align plane burn. So even slightly off this calculation can be useful for you in many situations. It's very more satisfying to calculate that yourself than simply blindly read what others tell you to do. If you want to launch southbound simply do 180°-45.075° = 134.925° (« 180-45.075 ENT » on calculator)