A lot of people have said they have no clue where the observatory is, so we made a step by step guide.
Start in the science complex, by the bio building facing the fountain. Those two domes are the observatories!
Walk across the courtyard towards that arch.
Walk under the arch. There should be a door on the left.
Go in the door, and you should see a wooden door on your right to the stairs.
Go through the wooden door and into the stairwell.
Go up the first flight of stairs.
You are now on the second floor. You want floor 4.
Go up the second flight of stairs.
You are now on the third floor. Keep going. We know its tough. We believe in you.
Go up the third and last flight of stairs.
These stairs end in a door to the fourth floor. Go through it.
Once you turn left, there should be a wooden door straight ahead. This is the observatory!
Double check that the room is P-401A, and then knock or come in! If the observatory is open we will be there. If it's nice out (summer+spring) and nobody is in the observatory, we may be on the roof. Check the metal door that was on your right as you entered the fourth floor.