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Residents report briefly seeing a column of heavenly light coming out of the sky. Apocalypse predictors haven't been this excited since the war.— After completion of That Lucky Old Sun, with power routed to ARCHIMEDES II.

Euclid's C-Finder is a unique weapon in Fallout: New Vegas.


Father Elijah was searching for the weapon, stating that someone must have scavenged it and sold it on the Strip.[1] Sarah Weintraub mentions that she had it at one point, but sold it to a man wearing a strange collar.[2] Currently, a child named Max is in possession of it, using it as a toy, chasing another child, Stacey, around Freeside with it.


The C-Finder is a handheld rangefinder linked to an orbiting laser weapon, the ARCHIMEDES II. Firing Euclid's C-Finder will result in a five-second delay and an animated sequence on the weapon's display before the impact. Euclid's C-Finder is not influenced by the player character's Energy Weapons skill.

Pressing the trigger constitutes firing the weapon, which will alert nearby enemies. The weapon can only be used once every 24-hours in-game, and does not work indoors. Euclid's C-Finder can fire a total of about 3995 times from full condition before breaking.


In Freeside, outside of Mick & Ralph's, the player character can find Max during the day. The player character can pay Max 1000 bottle caps, or 20 bottle caps with a Barter skill of 45 or more. Otherwise, the player character can wait until Max goes to bed, usually after 9 pm, then pickpocket the weapon from him, resulting in a loss of Karma.

Related quests

  • That Lucky Old Sun: In order to use Euclid's C-Finder, the player character must complete the quest and choose to direct power to ARCHIMEDES II at the end of the quest. If the player has already completed that quest without directing the power to ARCHIMEDES II, the C-Finder cannot be activated.


  • Euclid's C-Finder cannot be used in V.A.T.S.
  • If one has Veronica as a companion, she will respond "Yeah, I guess it works" when it is first fired.
  • The weapon will not always fire if the recharge time of 24 hours is waited using the "wait" function instead of in-game time.
  • Sometimes, around every two days, one may obtain another C-finder from Max if the player character chooses to use the Barter check. This can be repeated up to four times.
  • Even though Euclid's C-Finder is considered a unique weapon, there is no "normal" variant of it.
  • If one pickpockets the weapon from Max instead of buying it, he will later reappear chasing Stacey. He will not have the weapon equipped, but if one talks to him he will pull it out. The player character can then wait until it gets dark and pickpocket another from him.
  • After firing it for the first time, Mr. New Vegas will have a news article about the event on Radio New Vegas.
  • If the player character did not direct the power to ARCHIMEDES II at the end of That Lucky Old Sun, this can be reverted through the console command set "e282d".nPowerConfiguration to 4.
  • Aiming too close to the blast radius will prevent the C-Finder from working, notifying that "You are within the blast radius citizen, move further away."

Behind the scenes

The name Euclid's C-Finder, and the graphics it shows the player while it is operating, are a reference to using Euclidean geometry to find the third point, C, of a triangle, given points A and B, and distances BC and AC. In this example B is the player's position on the ground, A is the position of the ARCHIMEDES II satellite, and C is the position of the target.


  • Playstation 3Playstation 3 After exiting The Thorn or fast traveling with Euclid's C-Finder in your inventory, it may fire a beam with no warning, hitting The Courier, their companions and any other non-player characters in range. [verified]
  • PCPC Playstation 3Playstation 3 Xbox 360Xbox 360 It is possible Euclid's C-Finder may re-spawn multiple times on Max. If you do not have the gun in your inventory and return to Freeside sometime after acquiring it, Max will have another Euclid's C-Finder. This will also result in additional ARCHII charges added each day for each Euclid's C-Finder in the player character's inventory. [verified]
  • PCPC Playstation 3Playstation 3 Xbox 360Xbox 360 If the player character has the Heave, Ho! perk, firing Euclid's C-Finder may freeze the game. To fix this a player user can remove the perk using console commands, this will allow the player to fire the weapon without crashing. [verified]
  • PCPC Playstation 3Playstation 3 Xbox 360Xbox 360 When trying to fire, the targeting laser may repeatedly play its animation without the laser firing. To fix, save the game with the gun drawn and firing and then quit the game completely back to the desktop/reset console. Restart, reload, and wait for the firing animation to complete. Ensuring to save far enough away from the target to not be hit, but close enough that the animation is still visible and playing. [verified]
  • PCPC Playstation 3Playstation 3 Xbox 360Xbox 360 Sometimes the gun will not get any ammunition after activating ARCHIMEDES II, or it will fire a few times and then not get any more ammunition. To fix, save the game and then quit to the desktop/reset console. Reload the saved game and then after some time the charges will spawn as normal. [verified]
  • PCPC Playstation 3Playstation 3 Xbox 360Xbox 360 Sometimes Euclid's C-Finder will not fire at all, despite the lasers being visible. However, the orbital strike will still take place some time after this at the intended location. Entering a building and waiting or sleeping until midnight followed by staying inside for 5–10 minutes will prevent the delayed strike from occurring as the gun cannot be fired inside.[verified]
  • Playstation 3Playstation 3 Xbox 360Xbox 360 The game seems to register kills with Euclid's C-Finder as "unarmed" kills as evidenced by getting the Beautiful Beatdown perk while using it. [verified]
  • PCPC Xbox 360Xbox 360 Obtaining Euclid's C-Finder before completing or at least initiating the quest I Could Make You Care, could bug the quest. See the quest page for details. [verified]
  • Xbox 360Xbox 360 If aimed at a lake or body of water, there will be a bright flash of light, but no laser. [verified]
  • Playstation 3Playstation 3 Euclid's C-Finder may disappear from the player character's inventory after being caught stealing from the Silver Rush in Freeside, even after killing them. [verified]
  • PCPC Playstation 3Playstation 3 Xbox 360Xbox 360 If one obtains a second Euclid's C-Finder, DO NOT repair them. This may cause the bug in which it does not fire, and will show the laser marks only repeatedly even with another weapon out and may not fire. It is possible to fix this issue by removing the affected C-Finder from your inventory then buying or stealing a new one. [verified]
  • PCPC Playstation 3Playstation 3 Sometimes if the player character pickpockets the C-Finder, it will be in barely maintained condition instead of perfect. [verified]
  • PCPC Playstation 3Playstation 3 Xbox 360Xbox 360 The weapon may also fire immediately after loading a save chronologically after the laser was targeted so aim away from everything able to be killed. [verified]


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Euclid's C-Finder icon.png Euclid's C-Finder icon.png



  1. The Courier: "Tell me about the rangefinder."
    Veronica Santangelo: "It's a targeting device for some kind of doomsday weapon based at HELIOS One. It was lost sometime after the War. We held HELIOS One for a time. Lost a lot of people defending it. Too many. All for this weapon they never got working. If it turns out to be a dud, it'd show how flawed our goals have been. Father Elijah said he thinks a scavenger might have sold it on the Strip."
    (Veronica Santangelo's dialogue)
  2. The Courier: "I'm looking for an antique rangefinder somebody might've sold you."
    Sarah Weintraub: "Wow, I wish I had more of them. All this interest. It'd be my biggest seller. I sold it to a man not too long ago. Real twitchy, nervous sort of guy. Kinda seemed like he was wiggin' out about something. Had a funny collar on. I wanted to ask him about it but I figured maybe I'd regret asking. People are weird around here."
    (Sarah Weintraub's dialogue)