Alderaan Datacron Locations
There are 5 Datacrons on Alderaan.
Datacron 1 - Republic and Empire
Codex Entry - Galactic History 43: The Great Droid Revolution
This first Datacron is located in the Juran Mountains on a small island and is only reachable by a small trolly. Go to 1182, -99 and follow the snowy path up the mountain. At 1092, 0 jump onto a slow trolly and ride it to the island below.
Coordinates: 1106, 78
Datacron 2 - Republic and Empire
Codex Entry - Galactic History 45: The Krath Cult
The second Datacron is located in Glarus Valley at the Elysium Foundations. Go to -413, -209 where you will find a blue Thranta sitting in a nest. Ride it and it will drop you off at this Datacron. Just be careful when you land, you can easily fall off if you misstep.
Coordinates: -82, -267
Datacron 3 - Republic and Empire
Codex Entry - Galactic History 47: Naddist Rebels
The third Datacron is located in Castle Panteer. Inside the castle’s main lobby, on the left at -2490, -370 there is a door that has been forced open. Go thru the crack in the side of this door. Go up the staircase to the second floor. On the second floor, go around the right side of the room to reach the Datacron.
Coordinates: -2508, -426
Datacron 4 - Republic and Empire
Codex Entry - Galactic History 46: Nadd's Legacy
The fourth Datacron is located at the Lerantha Dam. First you have to stop by a Specialty Goods vendor named Lain-Ricie at 1869, 1091 in the Juran Mountains, and buy a MGGS (Magnetically Guided Grappling System) at a price of 10,000 credits. If you know someone that already has a MGGS, you can borrow theirs since it is not bound to the owner. After you buy the MGGS, go to 2172, -1990 and use the MGGS on the Magnetic Stabilizer. Its the blue electrical equipment just above the Datacron. Your MGGS will then pull you over to the Datacron.
Note: I have confirmed that you can now jump up the ladder that is located right beside this Datacron. If you don't want to use the MGGS, you can use this method to climb up to the Datacron.
Coordinates: 2191, -2019
Codex Entry - Galactic History 44: The Jedi Nomi
The fifth Datacron is located in the Ruur Killik Burrows. First you will need to go to the vendor mentioned above, Lain-Ricie at 1869, 1091 in the Juran Mountains, and buy a Red Detonite Actuator for 2,000 credits. This item has a single use and will be used to detonate the explosives in the cave to destroy a cave wall and expose the Datacron. If you are in a group, only one person needs to have the Red Detonite Actuator. After you have the Red Detonite Actuator, go to 2374, 2449 in King's Pass and fight your way through the cave to the point where the Datacron is. The Datacron is not visible until you blow the wall, so be sure to locate the coordinates inside on the map before venturing far into the cave. To reach the Datacron keep going straight towards the right from the endtrance on the cave map. Use the Red Detonite Actuator on the explosives on the wall to expose the hidden room with the Datacron.
Coordinates: 2721, 2496