ARC Raiders Ruins and Reverberations takes you to the Cielo Sereno Observatory on Pendola Pass. You need to attach a Spotter Relay to the roof antenna, weld the wires under the control room and return to the same roof to activate it.
All three interactions must happen in one raid, so arriving without the relay or extracting after the first roof visit will waste the attempt. Celeste supplies a Grappling Hook; the other essential preparation is getting a relay from a Spotter before you deploy.
ARC Raiders Ruins and Reverberations: Unlock the Observatory repair mission
Finish Wires Crossed, then accept ARC Raiders Ruins and Reverberations from Celeste in Speranza. Take the Grappling Hook she supplies, and bring one Spotter Relay salvaged from a defeated Spotter. Protect the relay in a Safe Pocket where possible, as losing it before reaching the roof leaves you unable to connect the antenna. The mission card specifies one round for the whole three-part sequence. You can’t attach the relay today and return tomorrow to weld it.
Find the Observatory on Pendola Pass
The Cielo Sereno Observatory is in northeastern Pendola Pass, above the Railroad Junction and Railyard approaches. Approach its main building and look for routes to the roof. A fixed ladder on the eastern side works, and you can also use a Grappling Hook to climb through a ceiling opening from inside. ARC Raiders Ruins and Reverberations is easier if you remember this route immediately, because you’ll need to get back to the same antenna after visiting the crawlspace.
Attach the relay to the roof antenna
Once on top, find the antenna on the western portion of the Observatory roof. Walk up until the Attach ARC Part or equivalent quest prompt appears, then install the Spotter Relay. Wait for the tracker to move to the wiring step before leaving. There are other antennas and structures visible across Pendola Pass, but this quest only accepts the one at Cielo Sereno. ARC Raiders Ruins and Reverberations has two separate interactions at the roof antenna, with a repair below ground between them.
Reach the crawlspace beneath the control room
Drop back through the roof opening into the Observatory’s interior. In the control room, find another opening through the floor and descend into the low crawlspace below. Follow the passage round its bends, turning left where it forks, until you reach the yellow electrical panel. It’s tucked beneath the room rather than in an obvious wall box upstairs. If you can’t find it, return to the floor opening in the control room instead of searching the exterior roof for a spare generator.
Weld the wiring without a tool
Interact with the yellow panel and hold its Weld prompt to redirect power. There is no separate Welding Tool required for this interaction, despite some early online descriptions saying otherwise. ARC Raiders Ruins and Reverberations advances when the panel itself finishes welding. If the objective hasn’t updated, make sure another player or ARC attack didn’t interrupt your hold interaction. Keep your Grappling Hook because the last stage sends you straight back to the rooftop.
Activate the antenna a second time
Climb out of the crawlspace and get back onto the Observatory roof by the ladder or grapple opening. Return to the antenna where you attached the relay. Its new interaction activates the repaired system; watch for the final quest confirmation before heading to extraction. ARC Raiders Ruins and Reverberations doesn’t require travelling to a second relay location. You can complete the sequence quickly if you move roof, crawlspace, roof instead of stopping to search the surrounding laboratories.
Claim rewards and fix common failures
Return to Celeste for two Smoke Grenades, one Looting Mk. 3 (Safekeeper), three Electrical Components and two Speaker Components, plus the quest’s listed experience reward. If the antenna has no attach prompt, check for the Spotter Relay item; if activation isn’t available, check that the yellow panel was welded. ARC Raiders Ruins and Reverberations starts over if you need a fresh run, so don’t leave the Observatory until the quest has explicitly ticked all three steps.
Related Guides
Official source: Embark Frozen Trail patch notes.
