Telescope

Michelle says: I know the way.
Wanna drive?
Sure.
Jack hands her the keys and the four get in the truck. James joins Michelle in the front, Annie and Jack take the rear seats. A few moments later, Michelle pulls onto the street in front of the bunker.
James asks her: How far is it?
A decent bit. Used to be about an hour on the highway. If it's in even somewhat decent shape, I'd say we're gonna make it there in about that time.
She turns right at an intersection onto the on-ramp, saying:
Gonna find out very soon...

The pavement is cracked and has potholes, and the highway is partially overgrown but, despite this, its condition is somehow good enough. Michelle floors it and the truck rattles and shakes as it accelerates on the uneven asphalt. James hangs on to the handle in the door as the remains of the city outskirts fly by. Michelle takes notice:
James, relax, that seat belt is gonna hold you.
How are you not absolutely terrified by the speed?
You get used to it after a while... Also, I know very well what I can or can't do with this car – I used to drive the same back then.

Within a few minutes, they make it out of Ivydale, leaving its valley behind. The mountains make way for an area of plains and shallow hills. The large, rusty signs above still indicate the proximity of Sentinel Shores where they haven't faded completely. Following them, Michelle takes an exit onto another highway that takes them north, around the western part of Ivydale's lower side.

After a while, they approach what used to be the outskirts of Sentinel Shores and Michelle takes an exit, getting them onto a rural road. The observatory is located on a hill, now ahead of them – a small group of buildings in the distance. As they get closer, the buildings take distinct shapes. Two of them stand out: The one in the center holds a large geodesic dome and another one off to the side behind it is a smooth round dome with a slot cut out of it for a telescope to peek through. Well, it was smooth at one point – now, it has many holes with a tree growing out of the largest one. The geodesic dome has ivy vines clinging to it but looks otherwise surprisingly intact. The other buildings look like mostly unremarkable ruins in various stages of decay.

Michelle says:
James, I'm sorry, but it doesn't look like you'll be able to look through that telescope – or anyone for that matter...
Aww, what a let-down. Might still find pictures there... Didn't you say you also need a telescope?
There are two telescopes here: The optical one back there and the radio telescope in that ball of triangles in the middle there. That's essentially just a really big antenna.
How does that work?
Stars emit light, but also other kinds of radiation. Radio telescopes were used to image that.
Can we do that?
A lot of things would have to go right for that.

She drives through what remains of an open gate, onto a large, overgrown paved area inbetween the buildings. She drives around the radio telescope and parks the truck between it and the optical telescope. They get out and look around. Trees and bushes grow all over the place, some even out of the buildings' walls. Dora runs up to one of the bushes and barks at it. A young fox jumps out and runs away.
Dora, c'mere!

They start by exploring the optical telescope. The lower part of the building is filled with some technology stuff, preferably not all computers and filing cabinets. Most of their contents are rotting sheets of paper holding documents and logs. Annie finds a folder with photos that are partially stuck together. The ones in the front depicting the outside of the observatory but there is at least one depicting a nebula.
James, look what I found.
He puts it into his backpack.

Meanwhile, Jack has found a way upstairs. The stairs are partially collapsed so he moves one of the filing cabinets in their place and climbs to the next floor.

Plot hole: geodesic dome bad. They start exploring in the optical telescope building - not wasting too much time there. Then, they go into the radome.