If you want to leave Vali a tip for writing this Alan Wake's American Nightmare guide you can do so here.
Alan Wakes American Nightmare Walkthrough Act III: Completed
Alan Wakes American Nightmare Act III: Completed
Alan will drive up to the observatory for the third (and hopefully) the last time.
Rachel will let you know that she has the imaging array set up and all you have to do is secure the primary coolant valves.
After securing the primary coolant system, you will get ambushed by numerous Taken.
After defeating all the Taken, you will have to destroy a car possessed by darkness that is blocking the entrance to the main observatory by using your flashlight's beam.
Once you've managed to get inside the main observatory, you will have to hold off the Taken until Dr. Rachel finishes receiving the signal, so she can shut down the telescope and turn the lights back on.
Make your way up to Dr. Rachel once the lights get back on.
Dr. Rachel is thrilled by the fact that time loops and men possessed by darkness exist.
After talking to Dr. Rachel, go and pick up the full signal printout.