Euclid's C-Finder

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

Background
Designed and developed 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. 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. 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. After some time, 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.

Characteristics
"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, capable of reducing many foes to ashes. 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 Euclid's C-Finder, the player character must complete the quest That Lucky Old Sun and choose to direct power to Archimedes II at the end of the quest. The weapon can only be used once every 24-hours in-game, due to the recharge time of the lasers. If the player has already completed that quest without directing the power to Archimedes II, the C-Finder cannot be activated.

Firing Euclid's C-Finder will result in a 5 second delay and an animated sequence on the weapon's display before the impact of the orbital laser strikes the ground. During the delay, Euclid's C-Finder can be repositioned for a new target before the laser strikes. Euclid's C-Finder is not influenced by the player's Energy Weapons skill. Pressing the trigger constitutes firing the weapon, which will alert nearby enemies before the actual laser hits. During this time, they may be able to move outside of the attack radius. 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).

Durability
Euclid's C-Finder can fire a total of about 3995 times from full condition before breaking. This would take approximately 11 game years were you to fire it once every day.

Location
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." Otherwise, the player character can wait until Max goes to bed, usually after 9 pm, then pickpocket the weapon from him, followed by a loss of Karma. The game has been known to display "talk" rather than "pickpocket" Max when doing this. If you press the interact button it will take you into the pickpocketing menu where you can steal the gun. This will result in no loss of Karma.

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 divisor 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, 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.

Bugs

 * 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, his/her companions and any other non-player characters in range.
 * 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 character's inventory.
 * 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.
 * 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.
 * 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.
 * 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.
 * 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.
 * 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.
 * If aimed at a lake or body of water, there will be a bright flash of light, but no laser.
 * 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.
 * If you obtain 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.
 * Sometimes if you pickpocket the C-Finder, it will be in barely maintained condition instead of perfect
 * 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.

Gallery
Euclids C-Detektor Buscador-C de Euclid Mire d'Euclide Euclid's C-Finder Алгоритм Эвклида 欧里几德的C型探测器