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Euclid's C-Finder
Euclid's C-Findercropped1.png
Euclid's C-Finder icon.png
SkillEnergy Weapons 0
Strength Req.1
Attack statistics
0 (0) + 150 (178.5) ExplosionIcon explosion.png
30.4 (36.2)
DPS (reload)
20.6 (24.6)
Crit Dmg
Crit % Mult
Ammo & reloading
Ammo TypeARCHIMEDES II charge
Ammo Cap.1
Reload Time
Item HP1000
Energy pistols
QuestsThat Lucky Old Sun
Editor IDWeapNVEuclidsCFinder
Base ID0014eb3c
Perk Effects
Perks (dam.)
Bloody Mess
(+0 +7.5 ExplosionIcon explosion.png)
Lord Death
(+0 +6 ExplosionIcon explosion.png)
Thought You Died
(+0 +15 ExplosionIcon explosion.png)

ARCHIMEDES II is an orbital laser. Effective only outdoors in a limited radius and requiring a long recharge.

Veronica Santangelo

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


Designed by Poseidon Energy for use in conjunction with Archimedes II orbital laser platform, however, the Euclid's C-Finder was nowhere to be found in Helios One, as found out by Father Elijah. He theorized that a scavenger must have gotten a hold of it some time prior to their arrival and sold it on the Strip.[1] This theory turned out to be true, sometime after Vault 21 was opened and turned into a hotel, Sarah Weintraub had acquired and then sold the C-Finder to the Man who was under the "persuasion" of Father Elijah to purchase it.[2] After acquiring the C-Finder, the Man ended up in Freeside where he tried to remove his slave collar but ultimately caused it to detonate and kill him.[3][4] After sometime, Max had come across the C-Finder the Man had bought and, thinking it was just a toy, began to chase his friend Stacey around Freeside with it.


The raw power of the sun, contained in an easy-to-carry package! Just point the handheld rangefinder at the bad guys, and pull the trigger!

The C-Finder is not a weapon per-se: it is actually a handheld rangefinder linked to an orbiting laser weapon, the Archimedes II. When used, it communicates with the platform, identifying the "C" (position of the target) and calling down the orbital strike. Due to a slight delay between marking the target and the actual strike, the target can be changed before the laser beam hits the designated area.

In order to use the weapon at all, the Archimedes II has to be powered up by directing power to it at Helios One. Once the energy is directed to a destination, the action cannot be reversed. Even when the weapon is active, the orbital laser can only be used once every 24 hours.

For obvious reasons, the rangefinder does not work indoors. It doesn't deal any direct damage either (all of the destruction comes from the laser beam).


In Freeside, outside of Mick & Ralph's, the player character can find Max during the day. Max thinks the weapon is actually just a toy, as it is reminiscent of the popular 1950s-60s toy laser guns for children. The player character can pay Max 1000 bottle caps, or 20 bottle caps with a barter skill of 45 or more, for his "toy gun" Euclid's C-Finder.

Otherwise the player character can wait until Max goes to bed, usually after 9pm, then pickpocket the weapon from him, followed by a loss of karma. The game has been known to say "talk" rather than "pickpocket" Max when doing this. The interact button activates the pickpocketing menu, where the rangefinder can be stolen at no karma loss.

You can buy multiples of the rangefinder by returning to Freeside after some time. If Max is chasing the girl again talk to him and he will have a new rangefinder.


  • Euclid's C-Finder cannot be used in V.A.T.S.
  • If you have Veronica as a companion, she will respond to the weapon when first fired saying "Yeah, I guess it works."
  • Though a heavy weapon of 15 lbs, Max, the child who owns it, has no problem holding it in one hand.
    • This may suggest that the weapon was originally intended to weigh 1.5 lbs instead, which would be consistent with a similar problem that Patch addressed, when it reduced the weight of several articles of clothing from 15 lbs to 1.5 lbs.
  • If you fire the weapon during its recharge time, the positioning lasers will be seen but the weapon will not fire, however the weapon will fire immediately after the recharge time is over.
  • The weapon will not always fire if the recharge time of 24 hours is waited using the wait-function instead of passing it in the game without the wait-function.
  • Because the game does not allow the player to kill children, they will be knocked out when hit by this weapon.
  • Euclid's C-Finder's reloading animation is exactly the same as the alien blaster's (when multiple charges are possessed), save for the C-Finder having an orange power cell, as opposed to the alien blaster's blue.
  • Euclid's C-Finder does not work indoors.
  • The sun ray causes a knock down effect in a large AoE where it is blasted so be careful with friendly fire, as your companions can be easily crippled by it.
  • After finishing That Lucky Old Sun, in third person, the C-Finder's display will fully display the 'notifications' that the C has been found, and the notification that the laser will strike down, but there's no laser that will strike down.

Behind the scenes

  • Euclid was a famous Greek mathematician, known as the originator of many basic geometric and mathematical principles. Euclidean geometry and Euclid's algorithm for calculating the greatest common factor of two integers are both named for him.
  • The name Euclid's C-Finder, and the graphics it shows the player while it is operating (see gallery below), 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. The satellite gets distance BC from Euclid's C-Finder (which is described as a "handheld rangefinder", in the terminal notes at HELIOS One), and knows AC, one assumes, from radar height measurement. In practice, the satellite would also need to be able to determine the direction Euclid's C-Finder is pointing. Presumably, Euclid's C-Finder can only measure basic compass heading and range, leaving the satellite to calculate the target's elevation, unless it had an internal gyroscope and GPS, which would allow the elevation of the target to be calculated.
  • Originally, the Euclid's C-Finder would've applied the Terrifying Presence perk effect against all hostile NPCs in the area where Archimedes II makes touchdown. However, this effect is left unused in the GECK. Compared to Euclid's C-Finder base effect used in-game, the only difference between the two effects is the Terrifying Presence perk effect.


  • PCIcon pc.png PlayStation 3Icon ps3.png Xbox 360Icon xbox360.png 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 some time 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 characters inventory.
  • PCIcon pc.png PlayStation 3Icon ps3.png Xbox 360Icon xbox360.png 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.
  • PCIcon pc.png PlayStation 3Icon ps3.png Xbox 360Icon xbox360.png 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.
  • PCIcon pc.png PlayStation 3Icon ps3.png Xbox 360Icon xbox360.png 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 the quit to the desktop/reset console. Reload the saved game and then after some time the charges will spawn as normal.
  • PCIcon pc.png PlayStation 3Icon ps3.png Xbox 360Icon xbox360.png Sometimes Euclid's C-Finder will not fire at all, only the lasers will be seen. However, the gun will also go off at a random time after this.
  • PCIcon pc.png Xbox 360Icon xbox360.png Obtaining Euclid's C-Finder before completing or at least initiating the quest I Could Make You Care, could bug the quest. See the page quest page for details.
  • PlayStation 3Icon ps3.png Xbox 360Icon xbox360.png 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.
  • PlayStation 3Icon ps3.png Euclid's C-Finder may disappear from the player characters inventory after being caught stealing from the Silver Rush in Freeside, even after killing them.
  • PlayStation 3Icon ps3.png 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 character's in range.
  • PlayStation 3Icon ps3.png Sometimes after activating Archimedes II the C-finder will have two charges, the first will fire normally, however the second will charge but will not fire. You will see the targeting laser animation - three lasers that circle the target and meet in the middle - but there will be no damage and as added downside the animation will loop indefinitely every 5–10 seconds following your crosshairs no matter what weapon you have equipped. The only known fix is to save the game, reload the the save, but this will however not fix the C-finder from firing blanks, just the targeting laser loop.
  • Xbox 360Icon xbox360.png If aimed at a lake or body of water, there will be a bright flash of light, but no laser.
  • Xbox 360Icon xbox360.png If you obtain a second Euclid's C-Finder, repairing them 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.



SingleShotVB.png BurstVB.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)
  3. The Courier: "What'd you tell him?"
    Sarah Weintraub: "I said I didn't know about anything like that around here. But if he wanted to live for free, a lot of people do that in Freeside. I know there's a concrete building there across from Mick and Ralph's. No ceiling, but I think it still counts. Went up there one time to try and... you know... meet my neighbors in the biz. But you know, I don't think they took me very seriously."
    (Sarah Weintraub's dialogue)
  4. The scene in which you find the Man in Freeside